President Donald Trump says the leaders of Russia and Ukraine have agreed to his request for a three-day ceasefire and an exchange of prisoners.
Mr Trump said that such a halt to hostilities could be the “beginning of the end” of the long war between them.
Mr Trump announced on social media that the ceasefire would run from Saturday through to Monday.
Saturday is Victory Day in Russia, a holiday that commemorates its victory over Nazi Germany 81 years ago in the Second World War.
Mr Trump wrote that he is “pleased to announce that there will be a three day ceasefire”.
The US president said the ceasefire includes a suspension of all kinetic activity and the exchange of 1,000 prisoners by each country.