President Donald Trump said Friday that the leaders of Russia and Ukraine agreed to his proposal for a three-day cease-fire and a prisoner exchange amid ongoing efforts to ease the conflict.

Trump said that such a halt to hostilities could be the "beginning of the end" of the long war between them.

He announced on social media that the cease-fire would run from Saturday through Monday. Saturday is Victory Day in Russia, a holiday that commemorates its victory over Nazi Germany 81 years ago in World War II.

Trump said he's "pleased to announce that there will be a THREE DAY CEASEFIRE." The Republican president said the cease-fire includes a suspension of all kinetic activity and the exchange of 1,000 prisoners by each country.