European allies have rallied behind Ukraine in a renewed surge of support, insisting that any peace talks with Russia must include Kyiv.
A joint statement issued by the leaders of the UK, France, Italy, Germany, Poland, Finland and the European Commission came ahead of US President Donald Trump's meeting with his Russian counterpart Vladimir Putin in Alaska on Friday.
A White House official has said that Trump is willing to hold a trilateral meeting which would also include Ukrainian President Volodymyr Zelensky, but, for now, it remains a Trump-Putin summit, as initially requested by the Russian leader.
Zelensky has said any agreements without Kyiv will amount to "dead decisions".
Trump has previously suggested that he could start by meeting only with Putin, telling reporters he planned to "start off with Russia." But the US president also said that he believed "we have a shot at" organising a trilateral meeting with both Putin and Zelensky.
Whether Putin would agree to this is unclear - he has refused several opportunities to hold direct talks, and the two leaders have not met face-to-face since Putin launched a full-scale invasion of Ukraine more than three years ago.
Speaking on Friday, Trump also suggested that there "will be some swapping of territories" in order for Moscow and Kyiv to reach an agreement - to which Zelensky reacted strongly.
"We will not reward Russia for what it has perpetrated," he said on Telegram. "Any decisions against us, any decisions without Ukraine, are also decisions against peace."
"The Russians... still impose the idea of 'exchanging' Ukrainian territory for Ukrainian territory, with consequences that guarantee nothing but more convenient positions for the Russians to resume the war," he added defiantly.
CBS, the BBC's US media partner, has reported that the White House is trying to sway European allies to accept an agreement that would include Russia taking the entire Donbas region in eastern Ukraine, and keeping the Crimean Peninsula.
The European leaders, in their statement released late on Saturday night, stressed that "international borders must not be changed by force".
"Ukraine has the freedom of choice over its own destiny," they said, stressing that their nations would continue to support Ukraine diplomatically, militarily and financially.
US diplomacy with Europe and Ukraine fell to Vice-President JD Vance on Saturday, when he visited the UK and held talks with Foreign Secretary David Lammy as well as two of Zelensky's top aides.
Thanking Vance for the discussions, Andriy Yermak, the head of Zelensky's office, stressed the need for Ukraine to be included.
"A reliable, lasting peace is only possible with Ukraine at the negotiating table," he said. "A ceasefire is necessary - but the frontline is not a border."
The summit in Alaska, the territory which Russia sold to the US in 1867, would be the first between sitting US and Russian presidents, since Joe Biden met Putin in Geneva in June 2021.
Nine months later, Moscow sent troops into Ukraine.
In 2022, the Kremlin announced the annexation of four Ukrainian regions - Donetsk, Lugansk, Zaporizhzhia and Kherson - despite not having full control over them.
Moscow has failed to achieve a decisive breakthrough in its full-scale invasion, but occupies large swathes of Ukraine's eastern territory. Ukrainian offensives, meanwhile, have not been able to push the Russian forces back.
