Ukraine's President Volodymyr Zelenskyy says he would reject any Russian proposal to pull Ukrainian troops out of the eastern Donbas region as it would deprive Ukraine of defensive lines and open the way for Russia to conduct further offensives. The Ukrainian leader told reporters on Tuesday territorial issues should be discussed after Russia agrees to a ceasefire, and security guarantees for Ukraine should be an integral part of that discussion. Trump has suggested an exchange of territory might be part of any potential peace deal.

Zelenskyy said Russia's proposal was to halt its advances in other Ukrainian regions in exchange for Ukraine pulling back its forces from the Donbas in eastern Ukraine, which comprises the regions of Donetsk and Luhansk.

Zelenskyy said Ukraine still controlled about 30 per cent of the Donetsk region, or about 9,000 square kilometres, and had heavily fortified defensive lines and controlled strategic high ground there. Any pullout would create a launch pad for new Russian offensives, he said. "We will not leave Donbas. We cannot do this. Everyone forgets the first part our territories are illegally occupied, Zelenskyy told reporters at a briefing on Tuesday.

"Donbas for the Russians is a springboard for a future new offensive."

Trump-Putin meeting 'a listening exercise'

Trump's administration tempered expectations on Tuesday for major progress toward a ceasefire, calling his meeting with Putin a "listening exercise". Asked why Zelenskyy was not joining the US and Russian leaders at the Alaska summit, a White House spokesperson said the bilateral meeting had been proposed by Putin, and that Trump accepted to get a "better understanding" of how to end the war. "Only one party that's involved in this war is going to be present, and so this is for the president to go and to get a more firm and better understanding of how we can hopefully bring this war to an end," press secretary Karoline Leavitt told reporters. "You need both countries to agree to a deal."

Trump is open to a trilateral meeting with Putin and Zelenskyy later, Leavitt said.

Russia makes fresh advance

In one of the most extensive incursions so far this year, Russian troops advanced near the coal-mining town of Dobropillia, part of Putin's campaign to take full control of Ukraine's Donetsk region. Ukraine's military dispatched reserve troops, saying they were in difficult combat against Russian soldiers. Ukraine's military, meanwhile, said it had retaken two villages in the eastern region of Sumy on Monday, part of a small reversal in more than a year of slow, attritional Russian gains in the south-east. Russia, which launched its full-scale invasion of Ukraine in February 2022, has mounted a new offensive this year in Sumy after Putin demanded a "buffer zone" there. Ukraine and its European allies fear that Trump, keen to claim credit for making peace and seal new business deals with Russia's government, will end up rewarding Putin for his 11 years spent in efforts to seize Ukrainian territory, the last three in open warfare.