The mounting death toll in Ukraine has forced President Volodymyr Zelenskyy to consider concessions to Russia in order bring an end to the devastating conflict, but the specific elements of any peace deal his government may be discussing with Moscow remain a mystery to Western leaders, said U.S. and European officials.

The secretive rounds of meetings between Russian and Ukrainian negotiators could hold the key to ending the conflict but also carry broader implications for European security depending on how the warring parties settle their differences. If Russian President Vladimir Putin can use military force to compel political change in Ukraine, he could use the same tactic elsewhere, U.S. and European officials fear.

The prospects of a near-term deal look bleak, diplomats say, but mixed signals from Zelenskyy about how close he is to striking an agreement have only heightened anxiety about the trajectory of the negotiations.

Russia has sought to pummel Ukraine into submission through artillery barrages, cruise missile strikes and a severing of supply routes that have prompted a humanitarian disaster and forced more than 3 million people to flee the country.

Zelenskyy, however, has remained defiant, saying his country wants peace — but not at any cost.

“I’m ready for dialogue; we’re not ready for capitulation,” Zelenskyy told ABC News earlier this week, while vowing to continue fighting Russia for as long as necessary.

Zelenskyy reiterated that message in even stronger terms on Tuesday when the prime ministers of Poland, the Czech Republic and Slovenia traveled to Kyiv to meet him in a risky wartime visit. “He showed very little interest in a negotiated settlement and said Ukraine needed to keep fighting until Putin altered his demands,” said a diplomat familiar with the discussions, who like others spoke on the condition of anonymity to discuss sensitive meetings.

At the same time, Zelenskyy’s top negotiator, Mykhailo Podolyak, has hailed progress in negotiations with Russia and suggested a quick end to the fighting. “Their position has softened significantly,” Podolyak told PBS this week in reference to Russia. “We have much confidence that we will have a cease-fire in the coming days.”

The conflicting forecasts have led to some confusion among Western leaders who see limited movement toward reconciling Russia’s demands with what Ukraine would find acceptable. Moscow has called for the full demilitarization of Ukraine and for Kyiv to recognize the Crimean Peninsula, annexed by Moscow in 2014, as Russian territory and the breakaway regions of Donetsk and Luhansk as independent countries. Moscow has also called for the “de-Nazification” of Ukraine, a Kremlin term believed to mean the dissolution of the Zelenskyy government. Ukrainian officials have said all four demands are non-starters but have been open to discussing the issue of neutrality and the country’s relationship to NATO.

“There’s no indication on our end that the Ukrainians are suing for peace. They want to fight,” said a senior U.S. official.

When asked to account for some of Ukraine’s optimistic messaging about a deal, the official said “we’ve been puzzling over this too. We’ve been getting mixed messages.”

A second U.S. administration official said Ukraine’s statements suggest that Zelenskyy and his top aides haven’t come to a firm conclusion on what the Ukrainian people are willing to concede in exchange for a cease-fire and withdrawal of Russian troops.

“They just haven’t come up with a decision yet,” added a senior European official.

Others close to Zelenskyy say he is under extraordinary pressure to convey progress in negotiations with Russia even if the reality is less sanguine.

“Many Ukrainians are now suffering enormously. That puts our delegation under pressure to show some kind of progress in the talks,” said Yuri Vitrenko, the CEO of Naftogaz, the country’s largest state-owned oil and gas company.

“There are people in Ukraine who say ‘we don’t want to hear about talks, we want to fight until the end.’ But others are saying ‘at least try to negotiate.’ That’s why for the negotiating team, it’s important to be constructive,” he said.

The Ukrainian Embassy in Washington declined to comment.

Speculation about an emerging peace deal surged on Wednesday following a report in the Financial Times that Ukrainian and Russian negotiators discussed a 15-point draft on Monday that would see Kyiv renouncing its ambitions to join NATO and swear off hosting foreign military bases or weaponry in exchange for security guarantees from countries such as Britain, the United States or Turkey.

That same day, Russian Foreign Minister Sergei Lavrov said that Ukraine’s “neutral status is now being seriously discussed” and said the two sides “are close to agreeing.” A day earlier, Zelenskyy said Ukrainians “must admit” that the West has indicated Ukraine won’t be a member of NATO — remarks that seemed designed to prepare the Ukrainian people for concessions.

But officials from Russia and Ukraine later denied that the 15-point plan represented a possible solution, and Ukrainian officials said most of the reported document was merely a restatement of Russian positions.

Zelenskyy will have to sell any peace deal to his own people — a tricky task if he is forced to concede too much. He has been a wildly popular wartime president, but he was an unpopular peacetime one. And Ukraine’s westward ambitions have only been strengthened by Russia’s assault. Before February, many residents of cities like Kharkiv were sympathetic to Russia. Now much of the city has been reduced to rubble, and pro-Russian voices have turned into fiercely pro-Kyiv ones.

Any potential deal will also require buy-in from the West, which will need to lift sanctions on Moscow in exchange for its withdrawal of Russian forces.

But Secretary of State Antony Blinken said Wednesday that a simple withdrawal of troops may not meet a U.S. standard for sanctions relief. The United States “will want to make sure that anything that’s done is, in effect, irreversible, that this can’t happen again, that Russia won’t pick up and do exactly what it’s doing in a year or two years or three years.”

Some eastern flank NATO members also oppose a peace agreement that concedes too much to Putin for fear of the message it would send about violations of sovereignty and international law.

“If at the end of this, Putin comes away with anything but a clearly defined loss for him, that would destabilize European and international security unlike anything we’ve seen since the days of the Second World War,” said Jonatan Vseviov, the secretary general of the Estonian Ministry of Foreign Affairs.

But the desire to have Putin feel defeated could also make a middle-ground compromise impossible, officials acknowledged, spurring the Russian leader to keep fighting. European countries would be unlikely to roll back sanctions at the first sign of a peace deal but would wait until there are concrete signs it is actually being implemented and respected, a senior European diplomat said.

A middle path could be possible, involving Ukraine setting aside its ambitions to join NATO in exchange for the integration of the separatist eastern Ukrainian territories back into Kyiv-controlled Ukraine.

“The question is if Putin is capable of agreeing on what many will see as defeat,” said a European diplomat.

Even if Zelenskyy manages to strike a deal, implementing it could be difficult. Ukraine’s NATO aspirations were baked into its constitution in a 2019 amendment, and changing it again would require a lengthy process that culminates in a supermajority vote of parliament. Not all political forces in the country are ready to do that, and a supermajority isn’t a sure bet, said Alex Riabchyn, a former lawmaker who voted in favor of the 2019 change.

The other challenge, Riabchyn said, is that Zelenskyy has proved so powerful a wartime communicator that Ukrainians are united behind him, with high morale and a willingness to keep fighting. A deal that seems like a defeat might not be acceptable to Ukrainian society.

“Ukrainians believe we are winning this war, so they might not accept painful compromises,” said Riabchyn, who now advises the government. “They might feel this is a betrayal. Zelenskyy raised the aspiration lines very high.”

For now, U.S. and European officials say they do not see signs that Russia is stopping its attack. One key measure, officials said, was whether Russian troops were digging defensive lines to solidify control of the territory they have captured. That hasn’t started yet, signifying a likely intent to keep pushing forward, two defense officials said.

Russia’s public optimism about a deal is a source of interest for diplomats. Officials familiar with the negotiations attribute it to one of two strategies. One is that Moscow is serious because the Kremlin wants to roll back existing sanctions. The other is that Russia wants to create the impression of seriousness in a bid to head off even more sanctions.

Vitrenko, the Naftogaz executive, subscribes to the latter.

“Russians are now making this impression that there is progress with negotiations for a very obvious reason: they don’t want the West to impose tougher sanctions.”

Ultimately, what Ukraine will agree to, lies with Zelenskyy because of the way he has emerged as a figure of unity.

“It’s Zelenskyy who decides,” he said. “It’s about the spirit of a nation. Thousands of Ukrainians are dying. He’s a wartime leader, and it’s a huge responsibility.”

The Washington Post’s Greg Jaffe contributed to this report.