Russia announced Thursday it would be ordering troops to return from the border with Ukraine.
The call is an apparent end to a substantial military build-up of tens of thousands of soldiers over the last few weeks, which had alarmed Western powers.
Russia also pulled additional troops out of Crimea, the peninsula it annexed from Ukraine and occupied since 2014.
Russian Defence Minister Sergei Shoigu said he had ordered troops involved in exercises to return to their bases by May 1, as they had completed what he called an "inspection" in the border area.
However, military hardware will be left at a city near the border.
Russia said it will be used again in another big exercise later this year.
Moscow has not provided any troop numbers, but a Ukrainian spokeswoman said earlier this month Russia had deployed 50,000 new troops.
That's on top of a permanent contingent of soldiers kept at the border and in Crimea.
Ukrainian President Volodymyr Zelenskiy, who has invited Russian President Vladimir Putin to meet over the crisis, wrote on Twitter that the country "welcomes any steps to...deescalate the situation in Donbas," and that he was "Grateful to international partners for their support".
Ukraine's foreign minister told Reuters Kyiv did not know whether Moscow intended to launch an attack or not, and said the West must make clear it would stand with Ukraine if Russia did so to prevent such a decision.
U.S. State Department spokesman Ned Price said Washington was aware of Russia's troop withdrawal and was watching the situation on the border closely.
Last week, the U.S. expelled Russian diplomats and tightened sanctions over accusations that it had hacked computers and meddled in its elections, prompting tit-for-tat expulsions by Moscow.
Western countries have also urged Russia to free jailed opposition leader Alexei Navalny, who is on hunger strike.
In a major speech on Wednesday, a defiant Putin warned Western countries not to cross Russia's unspecified "red lines".