Ukrainian President Volodymyr Zelensky said Tuesday 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.
Zelensky also ruled out withdrawing troops from Ukraine's eastern Donbas region as part of a peace deal, after Trump suggested he and Putin 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 Trump seeks to broker an end to Russia's nearly three-and-a-half year invasion of Ukraine.
Zelensky, who is not scheduled to take part, has expressed concern that Russia will put forward hardline demands and that 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," 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.
Zelensky said Friday's summit would effectively postpone new US sanctions on Russia — sanctions that Trump had promised to impose if Putin refused to halt his war.
"First, he will meet on US territory, which I consider his personal victory. Second, he is coming out of isolation because he is meeting on US territory. Third, with this meeting, he has somehow postponed sanctions," Zelensky said.
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," Zelensky said.
On the battlefield, Zelensky warned 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 10 kilometers (six miles) deep in several spots. They all have no equipment, only weapons in their hands. Some have already been found, some destroyed, some taken prisoner. We will find the rest and destroy them in the near future," Zelensky said.
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 10 kilometers (six miles) 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 said Tuesday 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.
The Institute for the Study of War, a US-based think tank, said Russia was sending small sabotage groups forwards.
It said it was "premature" to call the Russian advances around Dobropillia "an operational-level breakthrough".
A Ukrainian military group that oversees parts of the front in the Donetsk region also said Russia was probing Ukrainian lines with small sabotage groups, describing battles as "complex, unpleasant and dynamic".
Trump has described his summit with Putin on Friday as a chance to check the Russian leader's ideas for ending the war.
European leaders have meanwhile sought to ensure respect for Kyiv's interests.
Russia, which invaded Ukraine in 2022, has made costly but incremental gains across the front in recent months and claims to have annexed four Ukrainian regions while still fighting to control them.
Ukrainian police meanwhile said that Russian attacks in the past hours had killed three people and wounded 12 others, including a child.
by Victoria LUKOVENKO