US Secretary of State Marco Rubio says a meeting between US and Ukrainian negotiators in Geneva has been "probably the best ... so far" in terms of progressing a potential peace deal between Russia and Ukraine.
Mr Rubio's comments followed a social media post by US President Donald Trump hitting out at Ukraine's leaders, accusing them of being ungrateful for American support during Russia's invasion.
Mr Trump also hit out at European nations for continuing to buy Russian oil.
"UKRAINE 'LEADERSHIP' HAS EXPRESSED ZERO GRATITUDE FOR OUR EFFORTS, AND EUROPE CONTINUES TO BUY OIL FROM RUSSIA," Mr Trump posted on his Truth Social platform.
Mr Trump also lamented the "human catastrophe" of the war, but did not directly criticise Moscow for its role.
"I INHERITED A WAR THAT SHOULD HAVE NEVER HAPPENED, A WAR THAT IS A LOSER FOR EVERYONE, ESPECIALLY THE MILLIONS OF PEOPLE THAT HAVE SO NEEDLESSLY DIED," he wrote.
In a response on X ahead of the talks, Ukrainian President Volodymyr Zelenskyy said blame for the conflict should be directed entirely at Russia and its president, Vladimir Putin.
He also sought to reassure the US president he was thankful for American support.
"Ukraine is grateful to the United States, to every American heart, and personally to President Trump for the assistance that — starting with the Javelins — has been saving Ukrainian lives," he wrote.
Rubio says peace process 'much further ahead' after talks
Mr Trump's post came shortly before Mr Rubio and special envoy Steve Witkoff met with European leaders in Geneva on Sunday to discuss a 28-point plan to end the war released by the White House on Friday.
The plan calls for Ukraine to cede territory it currently controls, accept limits on its military and renounce ambitions to join NATO, echoing many demands Russia has made in recent years.
Mr Zelenskyy has criticised the plan, saying his country faces the choice of either losing its dignity or losing the backing of a key ally, given the Trump administration is threatening to withdraw support if Kyiv does not accept the plan by Thursday.
Speaking to reporters midway through a meeting with a delegation from Ukraine, Mr Rubio said the talks had been "probably [the] best meeting and day we've had so far in this entire process".
He later said changes would be made to the plan to work towards a solution that both Ukraine and the US could support.
"Obviously this will ultimately have to be signed off with our presidents, although I feel very comfortable about that happening given the progress we've made," Mr Rubio said.
"We are much further ahead than when we began this morning."
He added that some issues still to be resolved included the role of the European Union and NATO in any potential peace process, but he said none of those issues seemed insurmountable.
European leaders, for their part, have voiced alarm at the Trump administration's plan.
An alternative peace plan put forward by the UK, France and Germany at the summit pushed back on proposed limits to Kyiv's armed forces and territorial concessions, according to a document seen by Reuters.
The document proposes that Ukraine's military be capped at 800,000 "in peacetime" rather than a blanket cap of 600,000 proposed by the US plan.
It proposes that Ukraine receive a security guarantee from the United States similar to NATO's Article 5 clause.
[EL: Zelenskyy post]And it further suggests "negotiations on territorial swaps will start from the Line of Contact" between Ukrainian and Russian forces, rather than pre-determining that certain areas should be recognised as "de facto Russian", as the US plan suggests.
Since the US plan was announced, there has been considerable confusion about who was involved in drawing it up. European allies said they had not been consulted.
Speaking after several rounds of talks between Ukraine and the US, Ukrainian negotiator Rustem Umerov said the latest version of the US draft plan for ending the war in Ukraine now included most of Kyiv's "key priorities".
"The current version of the document, although still in the final stages of approval, already reflects most of Ukraine's key priorities," he said.
"We look forward to further progress throughout the day."
ABC/wires
