Ukrainian President Volodymyr Zelensky has said that Russian counterpart Vladimir Putin had scored a "personal victory" by getting invited to talks with Donald Trump on US soil, and that the meeting further delayed sanctions on Moscow.
Mr Zelensky also ruled out withdrawing troops from Ukraine's eastern Donbas region as part of a peace deal, after Mr Trump suggested he and the Russian leader might negotiate a land swap to end the war.
The summit, set to take place in Alaska on Friday, will be the first between a sitting US and Russian president since 2021 and comes as Mr Trump seeks to broker an end to Russia's nearly three-and-a-half year invasion of Ukraine.
Mr Zelensky, who is not scheduled to take part, has expressed concern that Russia will put forward hardline demands and that Mr Trump will hammer out a deal that will see Ukraine cede swathes of territory.
"We will not withdraw from the Donbas ... if we withdraw from the Donbas today - our fortifications, our terrain, the heights we control - we will clearly open a bridgehead for the Russians to prepare an offensive," Mr Zelensky told reporters.
The Donbas encompasses the eastern Ukrainian regions of Lugansk and Donetsk, both of which Russia claims as its own and has sought to control since its invasion began in 2022.
Mr Zelensky said Friday's summit would effectively postpone new US sanctions on Russia - sanctions that Mr Trump had promised to impose if Mr Putin refused to halt his war.
"First, he will meet on US territory, which I consider his personal victory," Mr Zelensky said.
"Second, he is coming out of isolation because he is meeting on US territory. Third, with this meeting, he has somehow postponed sanctions."
Mr Zelensky also said he had received a "signal" from US envoy Steve Witkoff that Russia might agree to a ceasefire, without elaborating.
"This was the first signal from them," Mr Zelensky said.
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Russia advances
The Ukrainian leader also said that Moscow was not seeking peace in Ukraine and was instead preparing new attacks.
"We see that the Russian army is not preparing to end the war. On the contrary, they are making movements that indicate preparations for new offensive operations," he said in a statement on social media.
On the battlefield, he warned that Russia had made sharp advances near the coal mining town of Dobropillia and was planning new ground assaults on at least three different areas of the front line.
"Russian units have advanced 10km deep in several spots. They all have no equipment, only weapons in their hands," he said.
"Some have already been found, some destroyed, some taken prisoner. We will find the rest and destroy them in the near future."
A map published by Ukrainian battlefield monitor DeepState, which has close ties with Ukraine's military, showed Russia had made a double-pronged advance around 10km deep in a narrow section of the front line near Dobropillia.
Dobropillia, home to around 30,000 people before the war, has come under regular Russian drone attacks.
The advance also threatens the largely destroyed town of Kostiantynivka, one of the last large urban areas in the Donetsk region still held by Ukraine.
Russian forces have been accelerating their advances for months, pressing their advantage against overstretched Ukrainian troops.
The Ukrainian army has said that it was engaged in "difficult" battles with Russian forces in the east, but denied Russia had a foothold near Dobropillia.
"The situation is difficult and dynamic," it said in a statement.
EU leaders say Ukraine must have say on its future
European leaders have meanwhile sought to ensure respect for Kyiv's interests.
In a statement, 26 European heads of state and government said that Ukrainians must have the freedom to decide their future and a diplomatic solution must protect Ukrainian and European interests.
The statement, which was agreed late last night and published this morning, was endorsed by leaders of all EU member countries except Hungary.
Fearing privately that Mr Putin will team up with Mr Trump to force unacceptable compromises, European leaders plan to speak separately tomorrow with both Mr Zelensky and Mr Trump.
"Meaningful negotiations can only take place in the context of a ceasefire or reduction of hostilities," the EU leaders said, adding that "we share the conviction that a diplomatic solution must protect Ukraine's and Europe's vital security interests".
"Russia's war of aggression against Ukraine has wider implications for European and international security. We share the conviction that a diplomatic solution must protect Ukraine's and Europe's vital security interests," the statement reads.
"The European Union, in coordination with the US and other like-minded partners, will continue to provide political, financial, economic, humanitarian, military and diplomatic support to Ukraine as Ukraine is exercising its inherent right of self-defence.
"It will also continue to uphold and impose restrictive measures against the Russian Federation."
Taoiseach Micheál Martin said in a post on X that he joined fellow EU leaders to make "an important statement of our continued support for Ukraine and to uphold sanctions against Russia aimed at securing a ceasefire".
Today, I join fellow EU leaders in making an important statement of our continued support for Ukraine and to uphold sanctions against Russia aimed at securing a ceasefire.
— Micheál Martin (@MichealMartinTD) August 12, 2025
Ukraine deserves a just and durable peace. https://t.co/dghvBJAq12
A 'feel-out meeting'
Mr Trump has described his upcoming summit with Mr Putin as a "feel-out meeting" to gauge his ideas for ending the war in Ukraine.
Friday's summit will be the first face-to-face meeting between the two countries' presidents since Russia invaded Ukraine in February 2022 - while criticising Mr Zelensky for rejecting territorial concessions.
The US president has spent the first months of his second term in office trying to broker peace in Ukraine - after boasting he could end the conflict in 24 hours - but multiple rounds of talks, phone calls and diplomatic visits have failed to yield a breakthrough.
Mr Trump played down the possibility of a breakthrough in Alaska, but said he expected "constructive conversations" with Mr Putin.
"This is really a feel-out meeting a little bit," Mr Trump told reporters at the White House.
"We're going to see what he has in mind and if it's a fair deal, I'll reveal it to the European Union leaders and to NATO leaders and also to President Zelensky," Mr Trump said.
"I may say - lots of luck, keep fighting. Or I may say, we can make a deal."
What deal might emerge from the Trump-Putin summit?
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