The Biden administration is engaged in an 11th-hour scramble to provide Ukraine with billions of dollars in additional weaponry, a massive effort that is generating concerns internally about its potential to erode U.S. stockpiles and sap resources from other flash points, officials said.

The lame-duck initiative was spurred in part by Russia’s battlefield momentum and a fear among Ukraine’s fiercest advocates that once President-elect Donald Trump takes office Jan. 20, there will be an abrupt shift in U.S. policy toward the war.

Yet some in the administration have taken the view that no matter what Washington does, Kyiv’s military will remain outmatched without far more soldiers to sustain its fight. And even as they accelerate arms shipments, there is growing frustration with Ukraine’s leaders, who have resisted U.S. calls to lower the country’s draft age from 25 to 18.

In recent weeks, Russian forces have captured Ukrainian territory at the fastest pace since 2022, causing alarm in Washington. Administration officials say their end-of-term weapons push — accompanied by President Joe Biden’s decision to green-light missile strikes deep into Russian territory and the deployment of antipersonnel land mines long criticized by human rights groups — can give Kyiv some breathing room. But they are urging Ukrainian leaders to use the moment to expand their military beyond the 160,000 recruits Kyiv says it needs.

“We’re absolutely going to keep sending Ukraine weapons and equipment. We know that’s vital. But so, too, is manpower at this point,” White House spokesman John Kirby said last week. “In fact, we believe manpower is the most vital need they have. So we’re also ready to ramp up our training capacity if they take appropriate steps to fill out their ranks.”

One senior administration official said that although Ukraine’s firepower had waned with the slowdown of U.S. military aid before Congress in April approved $61 billion in additional funding, that’s less of a problem now.

“The munitions gap may not be completely closed between Ukraine and Russia, but it’s gotten a whole lot better. But on the manpower side, it’s just a question of math and physics,” this official said, speaking like others on the condition of anonymity to talk frankly about sensitive U.S. assessments of the state of the battle and the Biden administration’s strategy.

“I’m not trying to accuse Ukraine of anything. It’s a very challenging issue for them,” the official said. “But over the course of especially this last year, it’s just that they’re not mobilizing and training enough soldiers to replace battlefield losses.”

Ukrainian leaders say that recruitment efforts were adversely affected by the dwindling military aid earlier this year, with potential soldiers disinclined to volunteer when they could not be sure they would have any weapons to fire at their enemy, and that Western arms shipments continue to lag.

“It doesn’t make sense to see calls for Ukraine to lower the mobilization age, presumably in order to draft more people, when we can see that previously announced equipment is not arriving on time. Because of these delays, Ukraine lacks weapons to equip already mobilized soldiers,” Dmytro Lytvyn, a communications adviser to Ukrainian President Volodymyr Zelenskyy, posted on social media.

“Ukraine cannot be expected to compensate for delays in logistics or hesitation in support with the youth of our men on the front line,” he said.

The outcome of Biden’s efforts now will help to shape his foreign policy legacy after a single term that was rocked by the fall of Afghanistan, the largest land war in Europe since World War II and instability throughout the Middle East amid Israel’s response to a Hamas attack in October 2023.

Trump, meanwhile, has vowed to end the Ukraine war in “24 hours” once he takes office. He announced last week that he would name retired general Keith Kellogg to be his special envoy for Russia and Ukraine. Kellogg, a top national security official in Trump’s first administration, has proposed conditioning future U.S. support for Ukraine on its engaging in talks to end the conflict, but he has also suggested arming Kyiv even more aggressively to push the Kremlin to make concessions.

The future of security aid from Washington — by far Ukraine’s chief military backer — after Trump’s inauguration remains in doubt. Both Vice President-elect JD Vance and Trump confidant Elon Musk have voiced skepticism about continued U.S. aid to Ukraine.

Trump’s transition team did not immediately respond to a request for comment.

Russia’s military advances have unsettled the Biden administration, although the senior administration official and others said they did not expect a major breakdown of Ukraine’s defensive lines in the coming months even if Moscow continues to advance.

These officials cautioned, however, that the race to use the remainder of the $61 billion supplemental aid bill has the potential to strain the U.S. military. There is particular worry about the volume of air defense interceptors and some types of artillery shells being rushed to Ukraine. Both will be difficult to replace quickly, and those losses will diminish U.S. military readiness for other potential hot spots in the Middle East and Asia, one official said.

“U.S. readiness is at severe and serious risk” if other needs aren’t balanced against Ukraine’s, this official said.

One senior U.S. defense official said the chief risk of a near-term aid sprint for Ukraine, rather than the depletion of U.S. reserves, would be to other missions as the military devotes more air assets and personnel to moving a massive amount of equipment to Europe. “We have been looking at what would the options be … if we are directed to make that acceleration happen, and what the cost would be to other missions around the world,” the defense official said.

The senior administration official said the White House is weighing those conflicting demands as it pushes forward with its plans to help Ukraine, saying, “These are real trade-offs.” The White House made the calculation, though, that despite the challenges to U.S. stockpiles, it is better to send as much aid as possible to Ukraine given “all the repercussions that flow from the war in Ukraine to the rules-based international order and to other theaters around the world, and how autocratic states will learn lessons from this,” the official said.

Long term, U.S. officials say, the gap between Russian and Ukrainian recruiting efforts probably will end up being far more important in determining the course of the war. Ukraine’s exhausted military has been challenged by severely undermanned front-line units, as well as a slow-going mobilization and training effort. The Kremlin, meanwhile, is managing to expand its forces slightly, even though it is sustaining major losses, one of the officials said.

Zelenskyy lowered the draft age from 27 to 25 in April and did away with a sweep of exemptions to try to boost personnel numbers. But progress has been slow, to the Biden administration’s frustration. Officials say there is spare capacity to help train an entire brigade of Ukrainian recruits outside the country if only Kyiv sent people their way.

“The most decisive factor on the battlefield today is Ukrainian soldiers willing to fight to stabilize the front lines,” the official said.

Analysts tracking the conflict have in recent days reported a surge in Russian advances in western Donetsk oblast, putting the towns of Pokrovsk and Velyka Novosilka at risk and endangering Ukraine’s supply lines. But a senior U.S. defense official downplayed the threat of an immediate, large-scale breakthrough and attributed the Kremlin’s rapid gains to the flat and “pretty open” area south of Pokrovsk, which the official said is not heavily defended as Ukrainian forces fall back to more defensible positions.

“I anticipate once they get through that open terrain, and up against the more entrenched offenses that the Ukrainians have, it’ll become much more typical for them and you’ll return to the much slower pace of advance, the attritional grind that we’ve seen other times,” the senior U.S. defense official said.

This official likewise attributed Russian gains in the country’s Kursk region, where Ukraine is attempting to defend a cross-border incursion it launched this summer, to Moscow’s counteroffensive there. So far, the Kremlin’s gathering campaign — including forces supplied by ally North Korea — has allowed Moscow to recover slightly more than a third of the territory Ukraine seized.

Despite what the official called Ukraine’s “slow fallback” in Kursk, the official said that, unless either side significantly alters its level of effort and resources dedicated to Kursk, it will probably take Russia several months to fully dislodge Ukrainian forces from the territory.

The Pentagon is closely monitoring Kursk for indications of how the fight is affected by the Biden administration’s recent decision to drop a long-standing prohibition on firing U.S.-made missiles at targets deep within Russia, the senior U.S. defense official said. The Army Tactical Missile System (ATACMS) has a range of up to 190 miles. Ukrainian forces also have conducted strikes inside Russia employing the Storm Shadow, a longer-range British missile.

So far, the official said, those missiles have had only a “disruptive” effect on the overall fight, slowing the integration of North Korean forces.

The Kremlin has vowed consequences for Kyiv’s Western backers and recently fired a powerful new missile into Ukraine after those strikes inside Russia. The debut of the Oreshnik, a nuclear-capable, intermediate-range ballistic missile, came as Russia modified its nuclear policy, introducing new conditions that suggest Moscow could employ nuclear weapons in response to conventional attacks by Ukraine.

Biden administration officials downplayed the risk of further escalation with Russia, saying they continue to believe it is in neither side’s interest to gamble with direct war between the two nuclear powers.

Ukrainian officials acknowledge the difficulty their military faces.

The front line in Donetsk is “a hard situation, maybe even one of the hardest in the last period of the war,” a Ukrainian official said. “But it’s not hopeless.” Many analysts expected Ukraine to lose control of Pokrovsk two months ago.

The most intense fighting, the official said, is occurring around the eastern city of Kurakhove, where Russian forces are seizing between 200 to 300 meters each day. “The Russians have tanks in front of them to move mines,” the Ukrainian official said. “… They even use them to move provisions, logistics and ammunition to soldiers.”

In Kursk, some 60,000 Russian troops are tasked with expelling the Ukrainians and establishing a new buffer zone more than 20 miles inside Ukraine’s sovereign territory, the official said. “If we pull back,” this official added, “an army of 60,000 will follow us into our territory.”

Siobhán O’Grady reported from Kyiv.

previous coverage

• Putin signs off record Russian defense spending as top EU officials visit Kyiv
• What Putin’s nuclear-capable Oreshnik missile means for NATO security

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