On a sunny October morning, the nation's top intelligence, military and diplomatic leaders filed into the Oval Office for an urgent meeting with President Joe Biden. They arrived bearing a highly classified intelligence analysis, compiled from newly obtained satellite images, intercepted communications and human sources, that amounted to Russian President Vladimir Putin's war plans for a full-scale invasion of Ukraine.

For months, Biden administration officials had watched warily as Putin massed tens of thousands of troops and lined up tanks and missiles along Ukraine's borders. As summer waned, Jake Sullivan, the national security adviser, had focused on the increasing volume of intelligence related to Russia and Ukraine. He had set up the Oval Office meeting after his own thinking had gone from uncertainty about Russia's intentions, to concern he was being too skeptical about the prospects of military action, to alarm.

The session was one of several meetings that officials had about Ukraine that autumn — sometimes gathering in smaller groups — but was notable for the detailed intelligence picture that was presented. Biden and Vice President Kamala Harris took their places in armchairs before the fireplace, while Secretary of State Antony Blinken, Defense Secretary Lloyd Austin and Gen. Mark Milley, chairman of the Joint Chiefs of Staff, joined the directors of national intelligence and the CIA on sofas around the coffee table.

Tasked by Sullivan with putting together a comprehensive overview of Russia's intentions, they told Biden that the intelligence on Putin's operational plans, added to ongoing deployments along the border with Ukraine, showed that all the pieces were now in place for a massive assault.

The U.S. intelligence community had penetrated multiple points of Russia's political leadership, spying apparatus and military, from senior levels to the front lines, according to U.S. officials.

Much more radical than Moscow's 2014 annexation of Crimea and instigation of a separatist movement in eastern Ukraine, Putin's war plans envisioned a takeover of most of the country.

Using mounted maps on easels in front of the Resolute Desk, Milley showed Russian troop positions and the Ukrainian terrain they intended to conquer. It was a plan of staggering audacity, one that could pose a direct threat to NATO's eastern flank, or even destroy the post-World War II security architecture of Europe.

As he absorbed the briefing, Biden, who had taken office promising to keep the country out of new wars, was determined that Putin must either be deterred or confronted, and that the United States must not act alone. Yet NATO was far from unified on how to deal with Moscow, and U.S. credibility was weak. After a disastrous occupation of Iraq, the chaos that followed the U.S. withdrawal from Afghanistan, and four years of President Donald Trump seeking to undermine the alliance, it was far from certain that Biden could effectively lead a Western response to an expansionist Russia.

Ukraine was a troubled former Soviet republic with a history of corruption, and the U.S. and allied answer to earlier Russian aggression there had been uncertain and divided. When the invasion came, the Ukrainians would need significant new weaponry to defend themselves. Too little could guarantee a Russian victory. But too much might provoke a direct NATO conflict with nuclear-armed Russia.

This account, in previously unreported detail, shines new light on the uphill climb to restore U.S. credibility, the attempt to balance secrecy around intelligence with the need to persuade others of its truth, and the challenge of determining how the world's most powerful military alliance would help a less-than-perfect democracy on Russia's border defy an attack without NATO firing a shot.

The first in a series of articles examining the road to war and the military campaign in Ukraine, it is drawn from in-depth interviews with more than three dozen senior U.S., Ukrainian, European and NATO officials about a global crisis whose end is yet to be determined. Some spoke on the condition of anonymity to discuss sensitive intelligence and internal deliberations.

The Kremlin did not respond to repeated requests for comment.

As Milley laid out the array of forces on that October morning, he and the others summed up Putin's intentions. "We assess that they plan to conduct a significant strategic attack on Ukraine from multiple directions simultaneously," Milley told the president. "Their version of 'shock and awe.' "

According to the intelligence, the Russians would come from the north, on either side of Kyiv. One force would move east of the capital through the Ukrainian city of Chernihiv, while the other would flank Kyiv on the west, pushing southward from Belarus through a natural gap between the "exclusion zone" at the abandoned Chernobyl nuclear plant and surrounding marshland. The attack would happen in the winter so that the hard earth would make the terrain easily passable for tanks. Forming a pincer around the capital, Russian troops planned to seize Kyiv in three to four days. The Spetsnaz, their special forces, would find and remove President Volodymyr Zelenskyy, killing him if necessary, and install a Kremlin-friendly puppet government.

Separately, Russian forces would come from the east and drive through central Ukraine to the Dnieper River, while troops from Crimea took over the southeastern coast. Those actions could take several weeks, the Russian plans predicted.

After pausing to regroup and rearm, they would next push westward, toward a north-south line stretching from Moldova to western Belarus, leaving a rump Ukrainian state in the west — an area that in Putin's calculus was populated by irredeemable neo-Nazi Russophobes.

The United States had obtained "extraordinary detail" about the Kremlin's secret plans for a war it continued to deny it intended, Director of National Intelligence Avril Haines later explained. They included not only the positioning of troops and weaponry and operational strategy, but also fine points such as Putin's "unusual and sharp increases in funding for military contingency operations and for building up reserve forces even as other pressing needs, such as pandemic response, were under-resourced," she said. This was no mere exercise in intimidation, unlike a large-scale Russian deployment in April, when Putin's forces had menaced Ukraine's borders but never attacked.

Some in the White House found it hard to wrap their minds around the scale of the Russian leader's ambitions.

"It did not seem like the kind of thing that a rational country would undertake," one participant in the meeting later said of the planned occupation of most of a country of 232,000 square miles and nearly 45 million people. Parts of Ukraine were deeply anti-Russian, raising the specter of an insurgency even if Putin toppled the government in Kyiv. And yet the intelligence showed that more and more troops were arriving and settling in for a full campaign. Munitions, food and crucial supplies were being deposited at Russian encampments.

Biden pressed his advisers. Did they really think that this time Putin was likely to strike?

Yes, they affirmed. This is real. Although the administration would publicly insist over the next several months that it did not believe Putin had made a final decision, the only thing his team couldn't tell the president that autumn day was exactly when the Russian president would pull the trigger.

CIA Director William Burns, who had served as U.S. ambassador to Moscow and had had the most direct interactions with Putin of anyone in the Biden administration, described the Russian leader to the others as fixated on Ukraine. Control over the country was synonymous with Putin's concept of Russian identity and authority. The precision of the war planning, coupled with Putin's conviction that Ukraine should be reabsorbed by the motherland, left him with no doubts that Putin was prepared to invade.

"I believed he was quite serious," Burns said months later, recalling the briefing.

— — —

The intelligence had underscored the promise of Putin's own words. Three months earlier, in July, he had published a 7,000-word essay, "On the Historical Unity Between Russians and Ukrainians," suffused with grievance and dubious assertions. Russians and Ukrainians, he argued, were "one people" - an idea rooted in Putin's claims about "blood ties" — and Moscow had been "robbed" of its own territory by a scheming West.

"I am confident that true sovereignty of Ukraine is possible only in partnership with Russia," Putin wrote.

Just weeks before the essay appeared, Biden and Putin had held a June 16 summit that both declared was "constructive." At that point, Ukraine was a concern, but one that White House officials felt could be dealt with. As the White House delegation left the meeting, held in Geneva, a senior Biden aide would later recall, "we didn't get on the plane and come home and think the world was on the cusp of a major war in Europe."

But Putin's subsequent publication "caught our attention in a big way," Sullivan later said. "We began to look at what's going on here, what's his end game? How hard is he going to push?" As a precaution, on Aug. 27, Biden authorized that $60 million in largely defensive weapons be drawn from U.S. inventories and sent to Ukraine.

By late summer, as they pieced together the intelligence from the border and from Moscow, analysts who had spent their careers studying Putin were increasingly convinced the Russian leader — himself a former intelligence officer — saw a window of opportunity closing. Ukrainians had already twice risen up to demand a democratic future, free from corruption and Moscow's interference, during the 2004-2005 Orange Revolution, and the 2013-2014 Maidan protests that preceded Russia's annexation of Crimea.

While not a member of NATO or the European Union, Ukraine was now moving steadily into the Western political, economic and cultural orbit. That drift fed Putin's broader resentment about Russia's loss of empire.

In a grim actuarial assessment, the analysts concluded that Putin, who was about to turn 69, understood that he was running out of time to cement his legacy as one of Russia's great leaders — the one who had restored Russian preeminence on the Eurasian continent.

The analysts said Putin calculated that any Western response to an attempt to reclaim Ukraine by force would be big on outrage but limited in actual punishment. The Russian leader, they said, believed that the Biden administration was chastened by the humiliating U.S. withdrawal from Afghanistan and wanted to avoid new wars. The United States and Europe were still struggling through the coronavirus pandemic. German Chancellor Angela Merkel, the de facto European leader, was leaving office and handing power to an untested successor. French President Emmanuel Macron was facing a reelection battle against a resurgent right wing, and Britain was suffering from a post-Brexit economic downturn. Large parts of the continent depended on Russian oil and natural gas, which Putin thought he could use as a wedge to split the Western alliance. He had built up hundreds of billions of dollars in cash reserves and was confident the Russian economy could weather the inevitable sanctions, as it had in the past.

Presented with the new intelligence and analysis at the October briefing, Biden "basically had two reactions," Sullivan said. First, to try to deter Putin, they "needed to send somebody to Moscow to sit with the Russians at a senior level and tell them: 'If you do this, these will be the consequences.' "

Second, they needed to brief allies on the U.S. intelligence and bring them on board with what the administration believed should be a unified and severe posture of threatened sanctions against Russia, reinforcement and expansion of NATO defenses, and assistance for Ukraine.

Burns was dispatched to Moscow and Haines to NATO headquarters in Brussels.

Months later, Milley still carried in his briefcase note cards encapsulating the U.S. interests and strategic objectives discussed at the October briefing. He could recite them off the top of his head.

Problem: "How do you underwrite and enforce the rules-based international order" against a country with extraordinary nuclear capability, "without going to World War III?"

No. 1: "Don't have a kinetic conflict between the U.S. military and NATO with Russia." No. 2: "Contain war inside the geographical boundaries of Ukraine." No. 3: "Strengthen and maintain NATO unity." No. 4: "Empower Ukraine and give them the means to fight."

Biden's advisers were confident Ukraine would put up a fight. The United States, Britain and other NATO members had spent years training and equipping the Ukrainian military, which was more professional and better organized than before Russia's assault on Crimea and the eastern region of Donbas seven years earlier. But the training had focused nearly as much on how to mount internal resistance after a Russian occupation as on how to prevent it in the first place. The weapons they had supplied were primarily small-bore and defensive so that they wouldn't be seen as a Western provocation.

The administration also had grave concerns about Ukraine's young president, a former television comic who had come into office on a huge wave of popular support and desire for fundamental change but had lost public standing in part because he failed to make good on a promise to make peace with Russia. Zelensky, 44, appeared to be no match for the ruthless Putin.

Math was not in Ukraine's favor. Russia had more troops, more tanks, more artillery, more fighter jets and guided missiles, and had demonstrated in previous conflicts its willingness to pummel its weaker adversaries into submission, with no regard for the loss of civilian lives.

Kyiv might not fall as quickly as the Russians expected, the Americans concluded, but it would fall.

— — —

On Nov. 2, Burns was escorted into the Kremlin office of Yuri Ushakov, Putin's foreign policy adviser and a former ambassador to the United States. Ushakov's boss was on the other end of a phone line and spoke to Burns from the resort city of Sochi, where he had retreated during another wave of coronavirus infections in Moscow.

The Russian leader recited his usual complaints about NATO expansion, the threat to Russian security, and illegitimate leadership in Ukraine.

"He was very dismissive of President Zelensky as a political leader," Burns recalled.

Practiced at listening to Putin's tirades from his years in Moscow, Burns delivered his own forceful message: The United States knows what you're up to, and if you invade Ukraine, you will pay a huge price. He said he was leaving a letter from Biden, affirming the punishing consequences of any Russian attack on Ukraine.

Putin "was very matter-of-fact," Burns said. He didn't deny the intelligence that pointed toward a Russian invasion of Ukraine.

The CIA director also met with another of Putin's advisers, Nikolai Patrushev, an ex-KGB officer, from Putin's hometown of St. Petersburg, who ran Russia's Security Council.

Patrushev had thought Burns flew to Moscow to discuss the next meeting between Putin and Biden and seemed surprised that the CIA chief had come bearing a warning about Ukraine.

He almost exactly echoed Putin's grievances about history and NATO in his discussions with Burns. There seemed to be no room for meaningful engagement, and it left the CIA director to wonder if Putin and his tight circle of aides had formed their own echo chamber. Putin had not made an irreversible decision to go to war, but his views on Ukraine had hardened, his appetite for risk had grown, and the Russian leader believed his moment of opportunity would soon pass.

"My level of concern has gone up, not down," the spy chief reported back to Biden.

— — —

As Burns was speaking with Putin, Blinken was sitting down with Zelensky, in Glasgow, Scotland, on the sidelines of an international summit on climate change. He laid out the intelligence picture and described the Russian storm that was heading Ukraine's way.

"It was just the two of us, two feet from each other," Blinken recalled. It was a "difficult conversation."

Blinken had met before with the Ukrainian president and thought he knew him well enough to speak candidly, although it seemed surreal to be "telling someone you believe their country is going to be invaded."

He found Zelenskyy "serious, deliberate, stoic," a combination of belief and disbelief. He said he would brief his senior teams. But the Ukrainians had "seen a number of Russian feints in the past," Blinken knew, and Zelenskyy was clearly worried about economic collapse if his country panicked.

Blinken's presentation, and Zelenskyy's skepticism, set a pattern that would be repeated both privately and in public over the next several months. The Ukrainians could not afford to reject U.S. intelligence wholesale. But from their perspective, the information was speculative.

Zelenskyy heard the U.S. warnings, he later recalled, but said the Americans weren't offering the kinds of weapons Ukraine needed to defend itself.

"You can say a million times, 'Listen, there may be an invasion.' OK, there may be an invasion — will you give us planes?" Zelenskyy said. "Will you give us air defenses? 'Well, you're not a member of NATO.' Oh, OK, then what are we talking about?"

The Americans offered little specific intelligence to support their warnings "until the last four or five days before the invasion began," according to Dmytro Kuleba, Zelensky's foreign minister.

Less than two weeks after the Glasgow meeting, when Kuleba and Andriy Yermak, Zelensky's chief of staff, visited the State Department in Washington, a senior U.S. official greeted them with a cup of coffee and a smile. "Guys, dig the trenches!" the official began.

"When we smiled back," Kuleba recalled, the official said, " 'I'm serious. Start digging trenches. … You will be attacked. A large-scale attack, and you have to prepare for it.' We asked for details; there were none."

If the Americans became frustrated at Ukraine's skepticism about Russia's plans, the Ukrainians were no less disconcerted at the increasingly public U.S. warnings that an invasion was coming.

"We had to strike a balance between realistically assessing the risks and preparing the country for the worst … and keeping the country running economically and financially," Kuleba said. "Every comment coming from the United States about the unavoidability of war was immediately reflected in the [Ukrainian] currency exchange rate."

A number of U.S. officials have disputed Ukrainian recollections, saying they provided the Kyiv government with specific intelligence early on and throughout the lead-up to the invasion.

Yet when it came to Ukraine, U.S. intelligence was hardly an open book. Official guidance prohibited the spy agencies from sharing tactical information that Ukraine could use to launch offensive attacks on Russian troop locations in Crimea or against Kremlin-backed separatists in the east.

Ukraine's own intelligence apparatus was also shot through with Russian moles, and U.S. officials were leery of sensitive information ending up in Moscow's hands. After the war began, the Biden administration changed its policy and shared information on Russian troop movements throughout Ukraine, on the grounds that the country was now defending itself from an invasion.

— — —

At a side meeting during the Group of 20 conference in Rome at the end of October, Biden shared some of the new intelligence and conclusions with America's closest allies — the leaders of Britain, France and Germany.

In mid-November, Haines used a previously scheduled trip to Brussels to brief a wider circle of allies: NATO's North Atlantic Council, the principal decision-making body of the 30-member alliance. Speaking in a large auditorium, she limited her remarks to what the intelligence community believed the evidence showed, and didn't offer policy recommendations.

"A number of members raised questions and were skeptical of the idea that President Putin was seriously preparing for the possibility of a large-scale invasion," Haines recalled.

French and German officials couldn't understand why Putin would try to invade and occupy a large country with just the 80,000 to 90,000 troops believed to be massed on the border. Satellite imagery also showed the troops moving back and forth from the frontier. Others posited that the Russians were performing an exercise, as the Kremlin itself insisted, or playing a shell game designed to conceal a purpose short of invasion.

Most were doubtful, and noted that Zelensky seemed to think Russia would never attack with the ambition and force the Americans were forecasting. Didn't Ukraine understand Russia's intentions best?

Only the British and the Baltic states were fully on board. At one point, an official from London stood up and gestured toward Haines. "She's right," the official said.

But Paris and Berlin remembered emphatic U.S. claims about intelligence on Iraq. The shadow of that deeply flawed analysis hung over all the discussions before the invasion. Some also felt that Washington, just months earlier, had vastly overestimated the resilience of Afghanistan's government as the U.S. military was withdrawing. The government had collapsed as soon as the Taliban entered Kabul.

"American intelligence is not considered to be a naturally reliable source," said François Heisbourg, a security expert and longtime adviser to French officials. "It was considered to be prone to political manipulation."

The Europeans began to settle into camps that would change little for several months.

"I think there were basically three flavors," a senior administration official said. To many in Western Europe, what the Russians were doing was "all coercive diplomacy, [Putin] was just building up to see what he could get. He's not going to invade . . . it's crazy."

Many of NATO's newer members in eastern and southeastern Europe thought Putin "may do something, but it would be limited in scope," the official said," … another bite at the [Ukrainian] apple," similar to what happened in 2014.

But Britain and the Baltic states, which were always nervous about Russian intentions, believed a full-scale invasion was coming.

When skeptical member states asked for more intelligence, the Americans provided some, but held back from sharing it all.

Historically, the United States rarely revealed its most sensitive intelligence to an organization as diverse as NATO, primarily for fear that secrets could leak. While the Americans and their British partners did share a significant amount of information, they withheld the raw intercepts or nature of the human sources that were essential to determining Putin's plans. That especially frustrated French and German officials, who had long suspected that Washington and London sometimes hid the basis of their intelligence to make it seem more definitive than it really was.

Some of the alliance countries provided their own findings, Haines said. The United States also created new mechanisms for sharing information in real time with their foreign partners in Brussels. Austin, Blinken and Milley were on the phone to their counterparts, sharing, listening, cajoling.

Over time, one senior European official at NATO recalled, "the intelligence was narrated repeatedly, consistently, clearly, credibly, in a lot of detail with a very good script and supporting evidence. I don't remember one key moment where the lightbulb went off" in the months-long effort to convince the allies, the official said. Ultimately, "it was the volume of the lights in the room."

— — —

Macron and Merkel had been dealing with Putin for years and found it hard to believe he was so irrational as to launch a calamitous war. In the weeks after Biden's Geneva meeting, they had tried to arrange an E.U.-Russia summit, only to be shot down by skeptical members of the bloc who saw it as a dangerous concession to Russia's aggressive posture.

Months later, despite the new U.S. intelligence, the French and Germans insisted there was a chance for diplomacy. The Americans and the British had little hope that any diplomatic effort would pay off, but were prepared to keep the door open — if the Europeans gave something in return.

"A big part of our focus," recalled Sullivan, "was basically to say to them, 'Look, we'll take the diplomatic track and treat it [as] serious … if you will take the planning for [military] force posture and sanctions seriously.'"

Each side was convinced it was right but was willing to proceed as if it might be wrong.

Over the next several months, the Americans strove to show the Western Europeans and others that they were still willing to search for a peaceful resolution, even though in the back of their minds, they were convinced that any Russian efforts at negotiation were a charade. "It basically worked," Sullivan said of the administration strategy.

On Dec. 7, Putin and Biden spoke on a video call. Putin claimed that the eastward expansion of the Western alliance was a major factor in his decision to send troops to Ukraine's border. Russia was simply protecting its own interests and territorial integrity, he argued.

Biden responded that Ukraine was unlikely to join NATO any time soon, and that the United States and Russia could come to agreements on other concerns Russia had about the placement of U.S. weapons systems in Europe. In theory, there was room to compromise.

For a while, as Blinken headed the U.S. diplomatic effort with repeated visits to NATO capitals and alliance headquarters in Brussels, the Ukrainians continued their contacts with European governments that still seemed far less convinced of Putin's intentions than the Americans were.

Kuleba and others in the government believed there would be a war, the Ukrainian foreign minister later said. But until the eve of the invasion, "I could not believe that we would face a war of such scale. The only country in the world that was persistently telling us" with such certainty "that there would be missile strikes was the United States of America. … Every other country was not sharing this analysis and [instead was] saying, yes, war is possible, but it will be rather a localized conflict in the east of Ukraine."

"Put yourself in our shoes," Kuleba said. "You have, on the one hand, the U.S. telling you something completely unimaginable, and everyone else blinking an eye to you and saying this is not what we think is going to happen."

In fact, the British and some Baltic officials believed a full invasion was probable. But Kuleba was far from alone in his skepticism. His president shared it, according to Zelensky's aides and other officials who briefed him.

"We took all of the information that our Western partners were giving us seriously," recalled Yermak, Zelensky's chief of staff. "But let's be honest: Imagine if all of this panic that so many people were pushing had taken place. Creating panic is a method of the Russians. … Imagine if this panic had started three or four months beforehand. What would've happened to the economy? Would we have been able to hold on for five months like we have?"

— — —

In early January, Deputy Secretary of State Wendy Sherman led a diplomatic delegation to Geneva and met with Sergei Ryabkov, her Russian counterpart, whom she knew well. He reiterated Moscow's position on Ukraine, formally offered in mid-December in two proposed treaties — that NATO must end its expansion plans and halt any activity in countries that had joined the alliance after 1997, which included Poland, Romania, Bulgaria and the Baltic states.

Rejecting the proposal to close NATO's doors and reduce the status of existing members, the administration instead offered talks and trust-building measures in a number of security areas, including the deployment of troops and the placement of weapons on NATO's eastern flank along the border with Russia. The offer was conditioned on de-escalation of the military threat to Ukraine. Ryabkov told Sherman that Russia was disappointed in the American attitude.

The White House had envisioned Sherman's meeting with Ryabkov as "a chance to test whether the Russians were serious about the substance of the concerns … and if there was a way forward for any kind of diplomacy," said Emily Horne, then the spokesperson for the National Security Council. "I think it became pretty clear, pretty quickly that [the Russians] were performing diplomacy, not actually undertaking diplomacy. They weren't even doing it with much seriousness."

"All the Western allies wanted to convey that there was an alternative path involving dialogue and respect for Russia as a great power," said a senior British government official involved in negotiations. "What became increasingly clear was that Russia was not interested in those."

As the United States pursued the diplomatic track, it also positioned forces to defend NATO, all of them visible to Moscow and to Europeans and demonstrating American willingness to put skin in the game. While Biden repeatedly said there would be no U.S. troops in Ukraine, the Pentagon increased pre-positioned weapons stocks in Poland and moved a helicopter battalion there from Greece. Paratroops from the 171st Airborne were deployed to the Baltic states. More troops were sent from Italy to eastern Romania, and others went to Hungary and Bulgaria.

Over the next several months, the U.S. military presence in Europe increased from 74,000 to 100,000 troops. Four airborne fighter squadrons became 12, and the number of surface combatant ships in the region increased from five to 26. Combat air patrols and surveillance were flying 24/7 missions over the alliance's eastern flank, with visibility deep inside Ukraine.

"We were saying, 'Look, we're taking diplomacy seriously, but we're so worried about this that we're actually moving men and material,'" Sullivan recalled.

With National Security Agency authorization, the United States established a direct communication line from the Ukrainian military to U.S. European Command. The highly secure system would keep the Americans in direct contact with their Ukrainian counterparts as events unfolded.

The administration was also sending arms to Ukraine. In December, Biden authorized an additional $200 million in weapons to be drawn from U.S. inventories — even as the Kyiv government, many in Congress and some within the administration itself argued that if the United States really believed a full-scale invasion was coming, it was not enough.

But every step in the administration campaign was premised on avoiding direct U.S. involvement in a military clash. The overriding White House concern about provocation influenced each decision about how much assistance and what kind of weapons to give the Ukrainians to defend themselves.

"I make no apologies for the fact that one of our objectives here is to avoid direct conflict with Russia," Sullivan said of the prewar period.

The Russians were going to do what they did regardless of what the allies did, a senior official involved in the decisions said, and the administration found "incredible" the notion, as some later argued in hindsight, that "if only we would have given" the Ukrainians more arms, "none of this would have happened."

Determining whether Russia would interpret a military exercise or a weapons shipment as provocative or escalatory was "more art than science," the official said. "There's not a clear and easy mathematical formula. … There has always been a balance between what is required to effectively defend, and what is going to be seen by Russia as the United States essentially underwriting the killing of huge numbers of Russians."

Ukrainian officials have expressed unending gratitude to the United States for what it has provided since the start of the war. "No other country in the world did more for Ukraine to get the necessary weapons than the United States since 24 February. No other country in the world," Kuleba said recently. But from the beginning, he said, he and other Ukrainian officials have believed that the "non-provocation" strategy was the wrong one.

"Where did it take us to?" Kuleba said. "I think this war — with thousands killed and wounded, territories lost, part of the economy destroyed … is the best answer to those who still advocate the non-provocation of Russia."

— — —

As part of its ongoing campaign to convince the world of what was coming — and dissuade the Russians — the White House decided toward the end of 2021 to challenge its own reluctance, and that of the intelligence agencies, to make some of their most sensitive information public.

U.S. intelligence had picked up on "false flag" operations planned by the Russians, in which they would stage attacks on their own forces as if they had come from Ukraine. Publicly exposing those plans might deny Putin the opportunity to concoct a pretext for invasion, administration officials reasoned.

As a first step, the White House decided to reveal the scale of the troop buildup that continued on Ukraine's borders. In early December, the administration released satellite photos, as well a map created by U.S. analysts showing Russian troop positions and an intelligence community analysis of Russian planning.

The analysis said the Russians planned "extensive movement" of 100 battalion tactical groups, involving up to 175,000 troops, along with armor, artillery and equipment. The picture that administration officials had been developing for weeks in secret was now seen around the world.

In anticipation of more selective disclosures of intelligence, Sullivan set up a regular process at the White House in which a team would determine whether a particular piece of information, if made public, could thwart Russian plans or propaganda. If the answer was yes, it would then be submitted to the intelligence community for recommendations on whether and how to release it.

In late January, the British government publicly accused Russia of plotting to install a puppet regime in Kyiv. The allegation, based on U.S. and British intelligence, was revealed in a highly unusual press statement by Foreign Secretary Liz Truss, late in the evening in London but just in time for the Sunday morning papers.

And in early February, the Biden administration disclosed that Moscow was considering filming a fake Ukrainian attack against Russian territory or Russian-speaking people — the false flag that intelligence had detected. The propaganda film would be heavy on spectacle, officials said, with graphic scenes of explosions, accompanied by corpses posed as victims and mourners pretending to grieve for the dead.

"I had watched Putin falsely set the narrative too many times," another U.S. official said. Now, "you could see him planning quite specifically in [eastern Ukraine] false flags. It was quite precise."

The intelligence disclosures themselves had an air of theatricality. The initial revelation of satellite pictures could be corroborated by commercial footage, though the analysis was unique to the intelligence community. But whether the public believed the subsequent disclosures depended on the government's credibility. And Biden administration officials knew they faced a public, at home and abroad, that could be deeply skeptical of "intelligence," following the Iraq War and the Taliban takeover in Afghanistan.

Broadly speaking, the U.S. public information campaign worked. World attention focused on the Russian troop buildup. The idea that Putin would falsify the reasons for his invasion seemed plausible, perhaps because in 2014 he had denied entirely that his troops were in Crimea, an assertion that led to descriptions of "little green men" in military uniforms without insignia occupying part of Ukraine.

Given how skeptical some allies remained about the intelligence, the most powerful effect of disclosing it was to shape Russian behavior and deprive Putin of the power to use misinformation, U.S. officials said.

— — —

On Jan. 12, Burns met in Kyiv with Zelenskyy and delivered a candid assessment. The intelligence picture had only become clearer that Russia intended to make a lightning strike on Kyiv and decapitate the central government. The United States had also discovered a key piece of battlefield planning: Russia would try to land its forces first at the airport in Hostomel, a suburb of the capital, where the runways could accommodate massive Russian transports carrying troops and weapons. The assault on Kyiv would begin there.

At one point in their conversation, Zelenskyy asked if he or his family were personally in danger. Burns said Zelenskyy needed to take his personal security seriously.

The risks to the president were growing. Intelligence at the time indicated that Russian assassination teams might already be in Kyiv, waiting to be activated.

But Zelenskyy resisted calls to relocate his government and was adamant that he not panic the public. Down that path, he thought, lay defeat.

"You can't simply say to me, 'Listen, you should start to prepare people now and tell them they need to put away money, they need to store up food,'" Zelensky recalled. "If we had communicated that — and that is what some people wanted, who I will not name — then I would have been losing $7 billion a month since last October, and at the moment when the Russians did attack, they would have taken us in three days. … Generally, our inner sense was right: If we sow chaos among people before the invasion, the Russians will devour us. Because during chaos, people flee the country."

For Zelenskyy, the decision to keep people in the country, where they could fight to defend their homes, was the key to repelling any invasion.

"As cynical as it may sound, those are the people who stopped everything," he said.

Ukrainian officials remained irritated that the Americans weren't sharing more about their intelligence sources. "The information that we received was, I would call it, a statement of facts without a disclosure of the origins of those facts or of the background behind those facts," Kuleba recalled.

But Western intelligence wasn't alone in thinking Zelenskyy should prepare for a full-scale invasion. Some of Ukraine's own intelligence officials, while still skeptical that Putin would strike, were planning for the worst. Kyrylo Budanov, Ukraine's military intelligence chief, said he moved the archives out of his headquarters three months in advance of the war and prepared reserves of fuel and ammunition.

The American warnings were repeated on Jan. 19 when Blinken made a brief visit to Kyiv for a face-to-face meeting with Zelenskyy and Kuleba. To the secretary's dismay, Zelenskyy continued to argue that any public call for mobilization would bring panic, as well as capital flight that would push Ukraine's already teetering economy over the edge.

While Blinken stressed, as he had in previous conversations, the importance of keeping Zelenskyy and his government safe and intact, he was one of several senior U.S. officials who rebuffed reports that the administration had urged them to evacuate the capital. "What we said to Ukraine were two things," Blinken later recalled. "We will support you whatever you want to do. We recommend you look … at how you can ensure continuity of government operations depending on what happens." That could mean hunkering down in Kyiv, relocating to western Ukraine or moving the government to neighboring Poland.

Zelenskyy told Blinken he was staying.

He had begun to suspect that some Western officials wanted him to flee so that Russia could install a puppet government that would come to a negotiated settlement with NATO powers. "The Western partners wanted to — I'm sure someone was really worried about what would happen to me and my family," Zelenskyy said. "But someone probably wanted to just end things faster. I think the majority of people who called me — well, almost everyone — did not have faith that Ukraine can stand up to this and persevere."

Similarly, warning Ukrainians to prepare for war as some partners wanted him to, he said, would have weakened the country economically and made it easier for the Russians to capture. "Let people discuss in the future whether it was right or not right," the Ukrainian leader recalled, "but I definitely know and intuitively - we discussed this every day at the National Security and Defense Council, et cetera — I had the feeling that [the Russians] wanted to prepare us for a soft surrender of the country. And that's scary."

— — —

In a news conference on Jan. 19, Biden said he thought Russia would invade. Putin had come too far to pull back. "He has to do something," the president said.

Biden promised that the West would answer Russia's attack. "Our allies and partners are ready to impose severe costs and significant harm on Russia and the Russian economy," he said, predicting that if Putin ordered an invasion, it would prove a "disaster" for Russia.

It was one of Biden's most forceful warnings to that point. But the president also muddied the waters, suggesting that a "minor incursion" by Russian forces, as opposed to a full-scale invasion, might not prompt the severe response that he and allies had threatened.

"It's one thing if it's a minor incursion, and then we end up having to fight about what to do and not do, et cetera," Biden said, signaling that NATO was not unified in its opposition to any Russian use of force. "If there's something where there's Russian forces crossing the border, killing Ukrainian fighters, et cetera, I think that changes everything," Biden said when, later in the news conference, a reporter asked him to clarify what he meant by a "minor incursion."

"But it depends on what he [Putin] does, actually, what extent we're going to be able to get total unity on the NATO front."

Biden's comments revealed the cracks in his own administration's planning, as well as in NATO. Blinken was in Kyiv, vowing that the United States would support Ukraine, in every way short of committing its own forces, if the country was attacked. But privately, administration officials had been contemplating for weeks how they would respond to a "hybrid" attack, in which Russia might launch damaging cyber-strikes on Ukraine and a limited assault on the eastern part of the country.

Zelenskyy and his aides, who still weren't convinced Putin would go to war, replied to Biden's comments about a "minor incursion" with a caustic tweet.

"We want to remind the great powers that there are no minor incursions and small nations. Just as there are no minor casualties and little grief from the loss of loved ones. I say this as the President of a great power."

Biden clarified the next day that if "any assembled Russian units move across the Ukrainian border, that is an invasion" for which Putin will pay. But White House officials quietly fumed that while the administration was trying to rally support for Ukraine, Zelenskyy was more interested in poking the president in the eye over an awkward comment.

"It was frustrating," said a former White House official. "We were taking steps that were attempting to help him, and there was a feeling that he was protecting his own political brand by either being in denial or projecting confidence because that's what was important to him at the time."

An aide to Zelenskyy who helped craft the tweet said it was meant to rebut Biden, but also to be light and humorous, a way to defuse the burgeoning tension. Zelenskyy's inner circle worried that Washington's predictions that war was around the corner would have unintended consequences.

As Biden was clarifying, Zelensky's team tried to assuage Washington with a conciliatory message.

"Thank you @POTUS for the unprecedented [U.S.] diplomatic and military assistance for [Ukraine]," Zelenskyy tweeted, with emoji of the U.S. and Ukrainian flags.

— — —

Jan. 21 was a cold, bleak day in Geneva, with gusty winds whipping the surface of the usually placid lake that shares the Swiss city's name. As Blinken and his aides sat across from their Russian counterparts at a table set up in the ballroom of a shoreline luxury hotel, the secretary offered the whitecaps as a metaphor. Perhaps, Blinken told Russian Foreign Minister Sergei Lavrov, they could calm the turbulent waters between their two countries.

They exchanged tense niceties and covered other issues — a spat about the size and activities of their embassies in each other's capital, the Iran nuclear deal — before turning to Ukraine. Blinken again laid out U.S. positions. If Putin had legitimate security concerns, the United States and its allies were ready to talk about them. But once an invasion of Ukraine began, Western sanctions would be fast and merciless, isolating Russia and crippling its economy, and the alliance would provide Ukraine with massive military assistance. If one Russian soldier or missile touched one inch of NATO territory, the United States would defend its allies.

Blinken found Lavrov's responses strident and unyielding. After an hour and a half of fruitless back-and-forth, it seemed there was little more to say. But as their aides began to file out of the ballroom, Blinken held back and asked the Russian minister to speak with him alone. The two men entered a small, adjacent conference room and shut the door as the U.S. and Russian teams stood uncomfortably together outside.

During Lavrov's nearly 18 years as Russia's foreign minister, a succession of American diplomats had found him blunt and doctrinaire, but occasionally frank and realistic about relations between their two countries. After again going over the Ukraine situation, Blinken stopped and asked, "Sergei, tell me what it is you're really trying to do?" Was this all really about the security concerns Russia had raised again and again - about NATO's "encroachment" toward Russia and a perceived military threat? Or was it about Putin's almost theological belief that Ukraine was and always had been an integral part of Mother Russia?

Without answering, Lavrov opened the door and walked away, his staff trailing behind.

It was the last time top national security officials of Russia and the United States would meet in person before the invasion.

Biden spoke with Putin once more by telephone. On Feb. 12, the White House said, he told the Russian president that "while the United States remains prepared to engage in diplomacy, in full coordination with our allies and partners, we are equally prepared for other scenarios."

— — —

A day earlier, British Defense Minister Ben Wallace had flown to Moscow to meet with his Russian counterpart, Sergei Shoigu, a longtime Kremlin survivor who helped sculpt Putin's tough-guy persona.

Wallace wanted to ask one more time if there was room for negotiation on Putin's demands about NATO expansion and alliance activities in Eastern Europe. The Russians, he said, showed no interest in engaging.

Wallace warned Shoigu that Russia would face fierce resistance if it invaded Ukraine. "I know the Ukrainians — I visited Ukraine five times — and they will fight."

"My mother's Ukrainian," Wallace said Shoigu replied, implying that he knew the people better. "It's all part of our same country."

Wallace then raised the prospect of sanctions. Shoigu responded: "'We can suffer like no one else.' And I said, 'I don't want anyone to suffer.'"

Shoigu aired a long and by now familiar list of complaints and said Russia couldn't tolerate Ukraine's Western trajectory. "It was in some respects incomprehensible," said a British official who attended the meeting. "Everyone wanted to keep negotiations going — we were throwing off-ramps, but they weren't taking them."

As the British officials were about to leave, Shoigu spoke directly to Wallace. "He looked me in the eye and said, 'We have no plans to invade Ukraine' " Wallace recalled. "That shows you how much of a lie it was."

A week later, on Feb. 18, Biden called the leaders of several NATO allies and told them the latest U.S. analysis. Biden told reporters in the Roosevelt Room at the White House later that day, "As of this moment, I'm convinced he's made the decision" to invade. "We have reason to believe that."

The French, however, continued to seek a way out of the crisis.

On Feb. 20, Macron called Putin and asked him to agree to a meeting in Geneva with Biden. The conversation led the French president to believe that Putin was finally willing to seek a settlement.

"It's a proposal that merits to be taken into account," Putin said, according to a recording of the conversation aired months later in a France TV documentary, "A President, Europe and War."

Macron pressed the Russian leader. "But can we say, today, at the end of this conversation, that we agree in principle? I would like a clear answer from you on that score. I understand your resistance to setting a date. But are you ready to move forward and say, today, 'I would like a [face-to-face] meeting with the Americans, then expanded to the Europeans'? Or not?"

Putin didn't commit and appeared to have more-pressing matters at hand. "To be perfectly frank with you, I wanted to go [play] ice hockey, because right now I'm at the gym. But before starting my workout, let me assure you, I will first call my advisers."

"Je vous remercie, Monsieur le President," Putin concluded, thanking him in French.

Macron is heard laughing in delight as he hangs up. The French president and his advisers thought they had a breakthrough. Macron's diplomatic adviser, Emmanuel Bonne, even danced.

But the following day, in a televised address, Putin officially recognized two separatist Ukrainian provinces in Donbas, including territory controlled by Kyiv, as independent states. It was a stark sign that Putin — his French-language pleasantries aside — intended to dismember Ukraine.

— — —

As Britain and France made last-ditch efforts at diplomacy, world leaders gathered in Munich for an annual security conference. Zelenskyy attended, prompting concerns among some U.S. officials that his absence might give Russia the perfect moment to strike. Others wondered if the Ukrainian leader believed Russia would attack and had used the opportunity to leave the country before the bombs started falling.

In a speech, Zelenskyy reminded the audience that his country was already at war with Russia, with Ukrainian troops fighting against the eastern separatists since 2014.

"To really help Ukraine, it is not necessary to constantly talk only about the dates of a probable invasion," Zelenskyy said. Instead, the European Union and NATO should welcome Ukraine into their organizations.

Some European officials were still unconvinced that an attack was coming. One told a reporter, "We have no clear evidence ourselves that Putin has made up his mind, and we have not seen anything that would suggest otherwise."

"It felt otherworldly," the British official said. In sideline conversations, U.S. and British officials were convinced of an imminent invasion, but "that just wasn't the mood in the hall."

Some in London began to doubt themselves, the British official said. "People were saying [we] got it wrong on Afghanistan. We returned and scrubbed the [Ukraine] intelligence again."

They came up with the same conclusion — Russia would invade. But despite the U.S. diplomatic and intelligence-sharing campaign, it remained a difficult sell.

"If you discover the plans of somebody to attack a country and the plans appear to be completely bonkers, the chances are that you are going to react rationally and consider that it's so bonkers, it's not going to happen," said Heisbourg, the French security expert.

"The Europeans overrated their understanding of Putin," he said. "The Americans, I assume … rather than try to put themselves in Putin's head, decided they were going to act on the basis of the data and not worry about whether it makes any sense or not."

There had been many reasons to be mystified. U.S. intelligence showed that the Kremlin's war plans were not making their way down to the battlefield commanders who would have to carry them out. Officers didn't know their orders. Troops were showing up at the border not understanding they were heading into war. Some U.S. government analysts were bewildered by the lack of communication within the Russian military. Things were so screwy, the analysts thought, Russia's plans might actually fail. But that remained a distinctly minority view.

For Kuleba, the turning point came in the days after the Feb. 18-20 Munich conference, when he traveled again to Washington. "These were the days I received more-specific information," he recalled. At a specific airport A in Russia, they told him, five transport planes were already on full alert, ready to take paratroops at any given moment and fly them in the direction of a specific airport B in Ukraine.

"That was where you see the sequence of events and the logic of what is happening," he said.

Western intelligence officials, looking back at what turned out to be the shambolic Russian attack on Kyiv, acknowledge that they overestimated the effectiveness of the Russian military.

"We assumed they would invade a country the way we would have invaded a country," one British official said.

— — —

Early in the evening of Feb. 23, the White House received an urgent intelligence flash. There was "high probability" that the invasion had begun. Troops were on the move, and the Russians had fired missiles on targets in Ukraine. The president's top advisers assembled; some met in the Situation Room while others joined on a secure line.

Sullivan spoke with Yermak, Zelensky's chief of staff. There was "an extremely high level of agitation" in Kyiv, said a person familiar with the call. "They were not spinning out of control. Just extremely emotional, but in a way you'd expect."

Yermak told Sullivan to hold on — he wanted to bring Zelenskyy to the phone to speak directly with Biden. Sullivan connected the call to the Treaty Room, part of the second-floor White House residence used as a study, and got the president on the line.

Zelensky implored Biden to immediately contact as many other world leaders and diplomats as possible. He should tell them to speak out publicly and to call Putin directly and tell him to "turn this off."

"Zelenskyy was alarmed," the person recalled. He asked Biden to "'get us all the intelligence you possibly can now. We will fight, we will defend, we can hold, but we need your help.'"

Harris reported from Washington and London; DeYoung from Washington, Brussels, and Joint Base Ramstein and Stuttgart in Germany; Khurshudyan from Kyiv; Parker from Washington; and Sly from London. Paul Sonne and Olivier Knox in Washington, Souad Mekhennet in Berlin, Rick Noack in Paris and Serhiy Morgunov in Kyiv contributed to this report.

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