Updated 4.10pm
Russia on Wednesday said military drills in Moscow-annexed Crimea had ended and that soldiers were returning to their garrisons, a day after it announced 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.
It comes a day after Moscow said it was pulling back some of the troops deployed on its neighbour's borders.
But Western leaders remain concerned that Russia could still launch an attack on Ukraine, with US President Joe Biden warning on Tuesday that an attack by Moscow remained "very much a possibility".
Biden said that despite Russian claims earlier in the day, Washington and its allies had yet to verify the withdrawal of any of the tens of thousands of troops he says Moscow has now mustered along Ukraine's border.
Secretary of State Antony Blinken said that the United States had seen no evidence of a significant Russian withdrawal of its military forces from Ukraine's borders, despite Moscow's claim.
"Unfortunately there's a difference between Russia says, and what it does and what we're seeing is no meaningful pullback," he said on ABC News.
"On the contrary, we continue to see forces, especially forces that would be in the vanguard of any renewed aggression against Ukraine, continuing to be at the border, to mass at the border."
Blinken called the threat of an invasion "real" and reiterated Washington's call for Russia to de-escalate the situation.
"President Putin has put in place the capacity to act on very short notice," the top US diplomat said.
"He can pull the trigger -- he could pull it today. He could pull it tomorrow. He could pull it next week. The forces are there if he wants to renew aggression against Ukraine."
Blinken urged diplomacy to resolve the situation, but added: "We're prepared for diplomacy. We're prepared for aggression. We're prepared either way."