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.

The leaked American ceasefire proposal would end sanctions on Russia, freeze the front line and see America formally recognise Russia’s annexation of Crimea. The intelligence officer, based in Kyiv, does not hide his disdain.

Russia and Ukraine blamed each other for breaking an Easter ceasefire announced by Vladimir Putin, with both sides accusing the other of carrying out attacks.