Ukrainian troops are still fending off Russian and North Korean forces in the Kursk region but face a potential new attack on Ukraine’s northeast Sumy region, President Volodymyr Zelenskiy said on Saturday.

Russia is close to ejecting Ukrainian forces from their months-old foothold in the western Russian region, prompting US President Donald Trump to say on Friday that thousands were “completely surrounded”.

In a statement on social media after being briefed by his top general, Zelenskiy said Kyiv’s troops were not encircled in Kursk but said Moscow was accumulating forces nearby for a separate attack.

“This indicates an intention to attack our Sumy region,” he said. “We are aware of this, and will counter it. I would like all partners to understand exactly what Putin is planning, what he is preparing for, and what he will be ignoring.”

Russian President Vladimir Putin said on Thursday he supported in principle Trump’s proposal for a 30-day ceasefire with Ukraine, but would fight on until several crucial conditions were worked out.

“The build-up of Russian forces indicates that Moscow intends to keep ignoring diplomacy,” Zelenskiy added. “It is clear that Russia is prolonging the war.”

In his statement, he also said fighting near the strategic eastern Ukrainian city of Pokrovsk had “stabilised”, and that Ukraine had successfully used a new domestically produced long-range missile in combat.