European and NATO leaders announced Sunday they will join Ukrainian President Volodymyr Zelenskyy in Washington for Monday's talks with U.S. President Donald Trump on ending Russia's war in Ukraine, with the possibility of U.S. security guarantees now on the negotiating table.

European leaders, including heavyweights France, Britain and Germany, are rallying around the Ukrainian leader after his exclusion from Trump's summit in Alaska on Friday with Russian President Vladimir Putin.

Their pledge to be at Zelenskyy's side at the White House on Monday is an apparent effort to ensure the meeting goes better than the last one in February, when Trump berated Zelenskyy in a heated Oval Office encounter.

"The Europeans are very afraid of the Oval Office scene being repeated and so they want to support Mr. Zelenskyy to the hilt," said retired French Gen. Dominique Trinquand, a former head of France's military mission at the United Nations. 

"It's a power struggle and a position of strength that might work with Trump," he said.

WATCH | Trump says Putin meeting was 'very productive': 

Trump calls meeting with Putin 'very productive'

U.S. President Donald Trump said he and Russian President Vladimir Putin agreed on many points during their talks Friday about the war in Ukraine, but about any formal agreement, he said, 'We haven't quite got there, but we've made some headway. So there's no deal until there's a deal.'

U.S. special envoy Steve Witkoff said Sunday that Putin agreed in Alaska to allow the U.S. and European allies to offer Ukraine a security guarantee resembling NATO's collective defence mandate as part of an eventual deal to end the 3 1/2-year war.

European Commission President Ursula von der Leyen, speaking at a news conference in Brussels with Zelenskyy, said: "We welcome President Trump's willingness to contribute to Article 5-like security guarantees for Ukraine. And the 'coalition of the willing' — including the European Union — is ready to do its share."

Canada is also a member of this coalition.

Macron, Starmer among leaders to join talks

Von der Leyen was joined Sunday by French President Emmanuel Macron, British Prime Minister Keir Starmer, German Chancellor Friedrich Merz and Finnish President Alexander Stubb in saying they will take part in Monday's talks at the White House, as will secretary-general of the NATO military alliance, Mark Rutte.

The European leaders' demonstration of support could help ease concerns in Kyiv and in other European capitals that Ukraine risks being railroaded into a peace deal that Trump says he wants to broker with Russia.

Neil Melvin, director of international security at the London-based Royal United Services Institute, said European leaders are trying to "shape this fast-evolving agenda." After the Alaska summit, the idea of a ceasefire appears all-but-abandoned, with the narrative shifting toward Putin's agenda of ensuring Ukraine does not join NATO or even the EU.

WATCH | Putin has warning for European countries following Alaska meeting: 

Putin has warning for Europe

Russian President Vladimir Putin, following his talks with U.S. President Donald Trump in Alaska Friday, said he hoped that Kyiv and other European capitals would not 'throw a wrench' into their work.

U.S. Secretary of State Marco Rubio said on NBC's Meet the Press on Sunday that a possible ceasefire is "not off the table" but that the best way to end the war would be through a "full peace deal."

Putin has implied that he sees Europe as a hindrance to negotiations. He has also resisted meeting Zelenskyy in person, saying that such a meeting can only take place once the groundwork for a peace deal has been laid.

Speaking to the press after his meeting with Trump, the Russian leader raised the idea that Kyiv and other European capitals could "create obstacles" to derail potential progress with "behind-the-scenes intrigue."

For now, Zelenskyy offers the Europeans the "only way" to get into the discussions about the future of Ukraine and European security, says RUSI's Melvin.

However, the sheer number of European leaders potentially in attendance means the group will have to be "mindful" not to give "contradictory" messages, Melvin said.

"The risk is they look heavy-handed and are ganging up on Trump," he added. "Trump won't want to be put in a corner." 

Zelenskyy stresses U.S., European role in talks

Although details remain hazy on what Article 5-like security guarantees from the U.S. and Europe would entail for Ukraine, it could mirror NATO membership terms, in which an attack on one member of the alliance is seen as an attack on all.

In remarks made on CNN's State of the Union, Witkoff said Friday's meeting with Trump was the first time Putin had been heard to agree to such an arrangement.

Zelenskyy continues to stress the importance of both U.S. and European involvement in any negotiations.

"A security guarantee is a strong army. Only Ukraine can provide that," he said at Sunday's news conference alongside von der Leyen. "Only Europe can finance this army, and weapons for this army can be provided by our domestic production and European production.

"But there are certain things that are in short supply and are only available in the United States."

Zelenskyy also pushed back against Trump's assertion — which aligned with Putin's preference — that the two sides should negotiate a complete end to the war, rather than first securing a ceasefire. Zelenskyy said a ceasefire would provide breathing room to review Putin's demands.

"It's impossible to do this under the pressure of weapons," he said. "Putin does not want to stop the killing, but he must do it."