Russia and Ukraine say they have exchanged captured soldiers - the first swap since the crash of a Russian plane that Moscow claimed had 65 Ukrainian prisoners of war (PoWs) on board.
Russia's military says each side got 195 soldiers back on Wednesday.
Ukraine's President Volodymyr Zelensky says 207 Ukrainian soldiers were returned.
Kyiv questions Moscow's claims that Ukrainian PoWs were on the plane that came down last week.
Russian President Vladimir Putin claimed on Wednesday that the Il-76 military transport plane had been downed by Ukraine in the western Belgorod region using an American Patriot system. He provided no proof.
The Russian military had previously said that dozens of Ukrainian soldiers were on the plane, which was heading to the area for a prisoner exchange. It said six Russian crew members and three escorting officials were also on board, adding that there were no survivors.
Russia has as yet produced no firm evidence of its claims and officials there have a long and proven history of lies and disinformation.
Kyiv has not directly denied the Russian statements but says that nothing has been confirmed.
Last week, a spokesman for military intelligence in Kyiv told the BBC that he "does not exclude" the possibility that PoWs were on the Il-76 plane.
Other official statements talk about Ukraine's right to defend itself from Russian missiles, particularly fired from Belgorod, near the Ukrainian border.
But many in Ukraine wonder why Russia has not shown images of dozens of dead bodies after the plane crash to back up its assertions.
None of the details have been independently verified and both sides have called for an international investigation.
Wednesday's exchange is the 50th PoW swap since President Putin launched a full-scale invasion of Ukraine in February 2022.
In a brief statement, the Russian defence ministry said the exchange was completed after negotiations.
"The released military personnel will be transported by military transport aircraft... to Moscow for treatment and rehabilitation," it said.
"All those released are provided with the necessary medical and psychological assistance," the statement said.
Footage released by the ministry purportedly shows those exchanged Russian soldiers boarding a bus before their flight to Moscow.
Meanwhile, President Zelensky wrote in a post on social media: "Our people are back. 207 of them. We return them home no matter what.
"We remember every Ukrainian in captivity. Both warriors and civilians. We must bring all of them back," he said, thanking Ukraine's top security officials for making the latest exchange possible.
Videos filmed by the Ukrainian authorities show the released PoWs spilling off buses, with big grins and shouts of "Glory to Ukraine!" One soldier drops to the ground, rolling in the snow, so overjoyed to be back.
The men are wearing Russian prison uniforms, their heads are close-shaven and many look gaunt after their time in captivity.
Some are in tears, talking to relatives by phone. At the end of the video they all stand, wrapped in Ukraine's national blue-and-yellow flags, and singing the country's anthem.
The exchange was kept secret until it happened, for security. Ukraine confirms that the United Arab Emirates was involved as a mediator, as it was earlier this month, but we do not know any details about the negotiations.
Ukraine's co-ordination centre for PoWs said among those released were National Guard members, border guards as well as one police officer.
Ukraine has said that none of the 65 men who were due for release last week, and who Russia claims were killed, are among the latest to be swapped.
However, a spokesman for Ukrainian military intelligence told the BBC some of the other soldiers who did return on Wednesday, had been due to be swapped in the last exchange.
The BBC has spoken to friends and relatives of the 65 still unaccounted for. They do not want to comment publicly, but stress that there is no evidence of anything at this point - and they remain hopeful.
"Of course, we're worried," a friend of one prisoner said. "But there is no information, no proof."
There are still thousands of Ukrainian PoWs being held in Russia.
Their families usually have no contact with them at all, and can know nothing about the men's fate until they are suddenly freed in a prisoner swap.
One woman, Tetyana, whose son was captured in Ukraine's south-eastern city of Mariupol in 2022, told the BBC she had heard nothing from her son directly ever since.
The last confirmation he was even alive was more than a year ago, when a prisoner who was released confirmed that they had shared a cell.
Tetyana described the agony of living with such uncertainty and having to convince herself each day that her son was still alive.