The United States and NATO have said Russia is still building up troops around Ukraine, despite Moscow's insistence it was pulling back, report agencies.
Russia has said military drills in Moscow-annexed Crimea had ended and that soldiers were returning to their garrisons.
However, NATO said the troop buildup was continuing, questioning Moscow's stated willingness to negotiate a solution to the crisis.
US Secretary of State Antony Blinken backed NATO's assessment in a morning television interview.
"There's what Russia says and then there's what Russia does. And we haven't seen any pullback of its forces," Mr Blinken told MSNBC.
"We continue to see critical units moving toward the border, not away from the border. What we need to see is exactly the opposite. We need to see these forces moving away."
NATO Secretary-General Jens Stoltenberg said a pullout would be welcome, but that moving troops and tanks back and forth did not amount to proof it was really happening..
"We have not seen any withdrawal of Russian forces. And of course, that contradicts the message of diplomatic efforts," Stoltenberg said before a meeting of the alliance in Brussels. "What we see is that they have increased the number of troops and more troops are on their way. So, so far, no de-escalation."
EU leaders will consider the "latest developments" regarding Russia's build-up of military forces.
Russia's announcement comes a day after it said a first troop pullback from Ukraine's borders.
"Units of the Southern Military District, having completed their participation in tactical exercises, are moving to their permanent deployment points," Moscow's defence ministry said in a statement.
State television showed images of military units crossing a bridge linking the Russia-controlled peninsula to the mainland.
The statement said tanks, infantry vehicles and artillery were leaving Crimea by rail.
US President Joe Biden made an impassioned appeal to Russian President Vladimir Putin to step back from war with Ukraine, speaking starkly of the "needless death and destruction" Moscow could cause and international outrage Mr Putin would face.
Mr Biden said the United States estimates that 150,000 Russian troops now encircle Ukraine, a higher number than previous estimates of about 100,000.
He said reports that some forces had withdrawn were welcome, but they were unverified and an invasion remained very much a possibility.
Meanwhile, Ukrainian President Volodymyr Zelensky has urged citizens to celebrate a "Day of Unity".
An intense diplomatic campaign is under way to head off the crisis triggered when Russia deployed more than 100,000 troops on Ukraine's borders, backed with fleet reinforcements and powerful artillery and missile systems.