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.

President Donald Trump said Wednesday that Vladimir Putin intends to retaliate “very strongly” against Ukraine for a surprise drone strike on Russian airfields over the weekend, a declaration that provoked alarm in Washington and abroad even as Trump touted his efforts to bring peace to the region.

Following a lengthy call, Trump said Putin could help bring Iran to a nuclear agreement and warned Tehran's delay must end soon.

President Vladimir Putin told U.S. President Donald Trump that he was ready to use Russia's close partnership with Iran to help with negotiations over Iran's nuclear programme, the Kremlin said on Thursday.

Iran’s Supreme leader has labelled Donald Trump “rude and arrogant” for trying to dismantle the Islamic Republic’s nuclear programme.