Trump predicts 'big week' in Russia-Ukraine peace talks

The president urged an end to the "bloodbath" in a social media post.

LONDON -- President Donald Trump suggested imminent progress in peace talks between Russia and Ukraine in a post to Truth Social early on Sunday, saying he would "continue to work with both sides" to end Moscow's 3-year-old invasion of its neighbor.

"A potentially great day for Russia and Ukraine!," Trump wrote. "Think of the hundreds of thousands of lives that will be saved as this never ending 'bloodbath' hopefully comes to an end. It will be a whole new, and much better, WORLD."

"I will continue to work with both sides to make sure that it happens." Trump continued. "The USA wants to focus, instead, on Rebuilding and Trade. A BIG week upcoming!"

Trump's efforts have so far failed to produce peace -- or even a lasting ceasefire -- between Russia and Ukraine, with fierce fighting and long-range strikes continuing since his return to the Oval Office in January.

The president has expressed frustration with both Ukrainian President Volodymyr Zelenskyy and Russian President Vladimir Putin over the failure of U.S.-led peace efforts.

Trump's latest remarks come after Putin announced a unilateral three-day ceasefire covering Russia's Victory Day celebrations, marking the anniversary of the Soviet Union's defeat of Nazi Germany in 1945. Ukraine -- which did not agree to the ceasefire -- said Russian forces repeatedly violated Putin's proposed pause in fighting. Putin's ceasefire ended on Saturday.

Zelenskyy instead offered a full 30-day ceasefire. On Sunday, following talks with the leaders of the U.K., France, Germany and Poland in Kyiv, Zelenskyy said in a Telegram post that he and his fellow leaders agreed that "a complete and unconditional ceasefire" should begin on May 12.

Putin has not agreed to Zelenskyy's proposal, though in a Sunday statement offered direct talks between Russia and Ukraine in Istanbul on Thursday.

"Russia is ready for negotiations without any preconditions," Putin said in a statement. "There is fighting going on right now, a war, and we are proposing to resume the negotiations that were interrupted not by us. What's wrong with that? Those who truly want peace cannot fail to support this."

In response, Zelenskyy said in a post to Telegram that Putin's offer was "a positive sign."

"The very first step in the real end of any war is a ceasefire," the Ukrainian president added. "There is no point in continuing the killings even for a day. We expect Russia to confirm a ceasefire -- complete, lasting and reliable -- starting tomorrow, May 12, and Ukraine is ready to meet."

ABC News' Victoria Beaule contributed to this report.