Ukraine has expressed readiness to accept a US proposal to enact an immediate 30-day ceasefire, while Russia has proposed only a three-day ceasefire to coincide with the 80th anniversary of the end of World War Two on Thursday.

Trump said in a social media post: "If the (30-day) ceasefire is not respected, the US and its partners will impose further sanctions." Trump has said he wants to the end the conflict in Ukraine but his administration has also threatened to abandon its attempts to broker a deal if Russia and Ukraine do not make headway.

Ukrainian President Volodymyr Zelenskiy said on Thursday he told Trump in a telephone call that Kyiv was ready for a 30-day ceasefire with Russia "starting this minute." Zelenskiy said Russia had to demonstrate its readiness to end the conflict, starting with an unconditional ceasefire.