Moscow’s forces are three miles from Dnipropetrovsk, a province they have never invaded. If they cross in, the advance would be a morale blow to Ukraine and complicate any territorial negotiations.

Russian forces have taken back more than 800 square km (309 square miles) of territory from Ukraine in the Kursk region of western Russia, or about 64% of the total taken by Ukraine since an incursion began last year,

European Union foreign policy chief Kaja Kallas said on Thursday that interactions between the United States and Russia showed Moscow had not given up its territorial goals in Ukraine, and that appeasing it would send a dangerous signal.