British Prime Minister Keir Starmer has told European leaders that they need to step up to a “once-in-a-generation moment” for the security of the continent, at a summit in London aimed at strengthening military cooperation and reaffirming support for Ukraine in its war against Russia.

Starmer said on Sunday that getting a good outcome for Ukraine was “vital to the security of every nation here and many others, too”.

He was flanked by Ukrainian President Volodymyr Zelenskyy and French President Emmanuel Macron during the official photo to mark the start of talks, which more than a dozen European leaders are attending.

Earlier on Sunday, Starmer said the United Kingdom, France and Ukraine had agreed to work on a ceasefire plan to present to the United States.

The summit is taking place two days after talks broke down between US President Donald Trump and Zelenskyy, when Trump blasted Zelenskyy for not being grateful enough for US support.

Sunday’s summit is likely to include talks on establishing a European military force to be sent to Ukraine to underpin a lasting ceasefire and ensure Ukraine can deter future Russian aggression.

European leaders are also set to prioritise increased economic pressure on Russia to strengthen Ukraine’s position.

Representatives from Germany, Denmark, Italy, Turkiye, NATO and the European Union are also attending the summit.

It comes before a summit in Brussels, scheduled to take place on Thursday, where the European Commission will announce a defence package for Europe, including Ukraine.

The package aims to bolster Ukraine’s defences and reinforce regional security, emphasising the need for a strong, lasting deal to safeguard Kyiv’s sovereignty. Ukraine’s European allies are seeking to address growing concerns over Trump’s approach to negotiations with Russia, which many fear could undermine Kyiv’s position.

Zelenskyy arrived in London on Saturday and was greeted by Starmer. The two leaders shared an embrace and announced a $2.84bn loan agreement to bolster Ukraine’s defence capabilities, funded by profits from frozen Russian assets.

Zelenskyy’s visit to London followed a tense encounter at the White House, where Trump and Vice President JD Vance criticised him for rejecting proposed truce terms and accused him of ingratitude. Trump also warned that Zelenskyy’s stance risked escalating the conflict into a global war.

Despite the heated exchange, Zelenskyy emphasised that Ukraine remains open to dialogue with the US.

“Despite the tough discussions, we remain strategic partners,” he wrote on X after his meeting. “But honesty and directness are essential to understanding our shared goals.”

European concerns

Trump’s recent overtures to Russian President Vladimir Putin have alarmed Kyiv and its European allies. The US president has positioned himself as a mediator between Putin and Zelenskyy, sidelining traditional diplomatic channels and prioritising rapprochement with Moscow.

Last week, Trump claimed “significant progress” had been made towards a peace deal in Ukraine, though details remain unclear.

But as the Ukrainian leader left the White House, Trump took to social media to say that Zelenskyy was not “ready for peace if America is involved”.

Following the spat, European leaders were quick to offer their support for the beleaguered Ukrainian leader.

Friedrich Merz, expected to be Germany’s next chancellor, addressed Zelenskyy on X, stating: “We stand with Ukraine in good and in testing times. We must never confuse aggressor and victim in this terrible war.”

Germany’s Foreign Minister Annalena Baerbock accused Trump of “reversing the roles of victim and aggressor” in the conflict, warning that his actions marked the beginning of a “new age of infamy”.

French President Emmanuel Macron told reporters that Russia is the “aggressor” in the Ukraine war and Ukrainians are the “aggressed people”.

Poland’s Prime Minister Donald Tusk wrote on X: “Dear Ukrainian friends, you are not alone.”