The US and Russia have exchanged jailed US basketball star Brittney Griner for notorious arms dealer Viktor Bout, held in an American prison for 12 years.

President Joe Biden said Griner was safe and on a plane home from the United Arab Emirates.

“I’m glad to say Brittney’s in good spirits… she needs time and space to recover,” he said at the White House.

Griner was arrested at a Moscow airport in February for possessing cannabis oil and last month sent to a penal colony.

The Biden administration proposed a prisoner exchange last July, aware Moscow had long sought Bout’s release.

Russia’s foreign ministry confirmed the swap and said it had taken place at Abu Dhabi airport. “The Russian citizen has been returned to his homeland,” it said in a statement, although he was not yet thought to have arrived on Russian soil.

Russian news agencies said he was still being flown to Vnukovo airport near Moscow.

Speaking in the Oval Office, Griner’s wife Cherelle praised the efforts of the Biden administration in securing her release: “I’m just standing here overwhelmed with emotions.”

As part of the prisoner exchange, President Biden signed the order for Bout’s release, commuting his 25-year jail term.

Viktor Bout sold arms to warlords and rogue governments, becoming one of the world’s most wanted men.

Dubbed the “merchant of death” for gun-running in the years after the fall of the Soviet Union, the Russian’s exploits inspired the 2005 Hollywood film Lord of War, which was loosely based on his life.

His secretive career was brought to an end by an elaborate US sting in 2008, when he was arrested at a hotel in the Thai capital Bangkok, to the anger of the Russian government.