Russia has freed jailed Ukrainian pilot Nadiya Savchenko, who became a symbol of resistance against Moscow, BBC reported.
"I am free," Savchenko told a crowd of reporters and politicians as she arrived in Kiev as part of a prisoner swap with two alleged Russian soldiers.
She was sentenced to 22 years in jail for killing two Russian journalists in eastern Ukraine, charges she denied.
The two Russians - Yevgeny Yerofeyev and Alexander Alexandrov - were earlier flown from Kiev to Moscow.
Savchenko was pardoned by Russian President Vladimir Putin before her return to Ukraine.
Mr Putin said he had acted after meeting relatives of the two Russian journalists, who had asked him to show mercy to Savchenko.
In Ukraine, President Petro Poroshenko pardoned the two Russian nationals.
In a tweet (in Ukrainian) earlier on Wednesday, Poroshenko wrote: "The presidential plane with Hero of Ukraine Nadiya Savchenko has landed!"
At a joint news conference with President Poroshenko later on Wednesday, Savchenko thanked her family and the people of Ukraine for supporting her while she was held in Russia.
"Ukraine has the right to be, and it will be!" she said, pledging to do everything she could to free all Ukrainian nationals still being kept prisoner in Russia and in parts of Ukraine controlled by pro-Russian rebels.
Meanwhile, President Poroshenko - who awarded Savchenko a Hero of Ukraine star - said: "This is our common victory!"
He also personally thanked German Chancellor Angela Merkel, French President Francois Hollande and US President Barack Obama for supporting Ukraine.
Reacting to Savchenko's release, EU foreign affairs chief Federica Mogherini described it as "long awaited good news, that the EU celebrates with her country", while German Foreign Minister Frank-Walter Steinmeier said it was "good news that we have long worked for".
Savchenko was captured in 2014, as pro-Russian separatists in Ukraine's eastern Donetsk and Luhansk regions battled government forces.
She was charged with directing artillery fire that killed the two journalists, but she says she was kidnapped prior to the attack and handed over the border to the Russian authorities.
Her time in jail saw her mount a hunger strike and she was even elected in absentia to Ukraine's parliament and the Parliamentary Assembly of the Council of Europe.