Russian President Vladimir Putin told President Donald Trump in a phone call Wednesday that he was obligated to respond to Ukraine’s weekend drone attack, Trump said, setting up a potential escalation in the conflict just as the US president hopes to broker an end to the war.

U.S. President Donald Trump says he's spoke with Russian President Vladimir Putin and that the Russian leader told him “very strongly” that he will respond to Ukraine’s weekend drone attack on Russian airfields.

President Trump said Russian President Vladimir Putin told him he would have to respond to Ukraine’s recent attack, dampening the prospects for immediate peace between Moscow and Kyiv.