Russian officials confirmed for the first time publicly that North Korean soldiers have been fighting alongside them in the war in Ukraine, as U.S. President Donald Trump shows his patience is running thin with Russia on peace talks in Ukraine.

US President Donald Trump said Russia and Ukraine are “very close to a deal” that would end their three-year war, after his envoy met with President Vladimir Putin on Friday in talks Moscow said were “constructive and very useful.

The president’s comments came after he said Crimea “will stay with Russia,” a position backed by the mayor of Kyiv, who conceded that his country may have to give up territory.