US President Donald Trump suggested that Ukraine's Volodymyr Zelenskyy has not read an American proposal for peace in Ukraine.
US mediators met last week with Russian President Vladimir Putin to present its proposal, which included revisions after talks with European officials.
"So we've been speaking to President Putin and we've been speaking to Ukrainian leaders — including Zelenskyy, President Zelenskyy — and I have to say that I'm a little bit disappointed that President Zelenskyy hasn't yet read the proposal, that was as of a few hours ago," Trump told reporters at the Kennedy Center Honors on Sunday night.
Trump's remarks came a day after talks between US and Ukrainian officials, in which Zelenskyy also took part, concluded after three days without a breakthrough.
Moscow has also rejected aspects of Washington's proposal.
Peace talks with US 'constructive' but 'not easy', Zelenskyy says
On the eve of his trip to London, Ukraine's President Volodymyr Zelenskyy described talks between Ukrainian and US officials in Florida last week as "constructive, although not easy."
Zelenskyy spoke to White House envoy Steve Witkoff and US President Donald Trump's son-in-law, Jared Kushner, who have been leading the US efforts to secure a peace deal that is agreeable to both Russia and Ukraine.
"The American representatives know the basic Ukrainian positions," Zelenskyy said in his nightly video address. "The conversation was constructive, although not easy."
The negotiations have stalled over long-term security guarantees for Ukraine and swathes of territory in eastern Ukraine that is occupied by Russia.
Moscow has blamed Kyiv and Europe for prolonging the war, with Ukraine and its European partners accusing Russian President Vladimir Putin of not engaging sincerely in the peace talks.
Starmer hosts Zelenskyy, Macron, Merz to talk peace plans
The UK Prime Minister Keir Starmer will meet with Ukrainian President Volodymyr Zelenskyy in London on Monday for the latest round of talks on ending Russia's war in Ukraine.
French President Emmanuel Macron and German Chancellor Friedrich Merz will also attend the meeting in Downing Street.
Their meeting will discuss how to break the deadlock in negotiations to end the nearly four-year war, Downing Street said Sunday night.
Despite a renewed diplomatic push in recent weeks led by the US, a ceasefire deal has proved elusive.
Ukraine's long-term security guarantees as well as the future of territory in eastern Ukraine occupied by Russia are among the main issues blocking progress in the negotiations.
UNGA president Baerbock rejects Ukrainian loss of territory in peace deal
UN General Assembly President Annalena Baerbock has said Ukraine should not have to cede any territory in a peace deal with Russia.
Germany's former foreign minister warned that rewarding Russia's aggression by agreeing to giving up territory would only lead to more war.
"You condemn an act of aggression, you do not reward it. Those who reward aggression will reap more war instead of peace," she said in comments published on Sunday by Germany's Funke media group.
Russia is demanding that Ukraine withdraw from the eastern Donbas region, large parts of which are occupied by Moscow's forces.
Ukraine has refused to accept those terms, despite increasing US pressure to agree to a deal.
Baerbock refused to discuss what role the UN might play in enforcing a potential ceasefire.
"First, there must be a ceasefire and a peace agreement, then we can discuss how it can be enforced," she said. "But for that, Russia would have to be willing to end the war first."
