US basketball star Brittney Griner has been freed in a prisoner swap.
The WNBA star was released in exchange for convicted Russian arms dealer Viktor Bout, known as the "Merchant of Death".
She had been imprisoned in Russia after being convicted in August and sentenced to nine years in prison.
Ms Griner was detained in February when customs agents said they found vape canisters containing cannabis oil in her luggage at Moscow's Sheremetyevo Airport.
President Joe Biden said he had spoken to Ms Griner and that she is "safe" and "on her way home".
She will be flown to a medical facility in San Antonio, Texas, where she will also meet her wife, Cherelle.
President Biden said Ms Griner had been held under "intolerable circumstances" and been through a "terrible ordeal".
"I'm glad to be able to say that Britney is in good spirits. She's relieved to finally be heading home."
Ms Griner "represents the best of America", he added.
President Biden stressed that the US has not forgotten about Paul Whelan, a former US marine who remains in Russian custody.
A senior US official said the administration tried everything they could to get Paul Whelan out, but "they are treating him differently. They say he is an espionage case. They said the choice was either one [Griner] or none."
He did not address the price the US paid for Ms Griner's liberty - the release of convicted arms dealer Bout.
Ms Griner's wife Cherelle said she was "overwhelmed with emotions" after going through "one of the darkest moments of my life".
"So today my family is whole, but as you all are aware, there's so many other families who are not whole."
The Griner-Bout swap took place in Abu Dhabi airport, according to the Russian Foreign Ministry.
"The Russian citizen has been returned to his homeland," it said in a statement.
Pressure on Washington over Griner case
For almost two decades, Bout was one of the world's most notorious arms dealers, selling weaponry to rogue states, rebel groups and murderous warlords in Africa, Asia, and South America.
Ever since his capture in an elaborate US sting, the Russian state has been keen to bring him back.
Biden's authorisation to release Bout underscores the escalating pressure that his administration has faced to bring Ms Griner home, particularly after the recent resolution of her criminal case and her subsequent transfer to a penal colony.
Ms Griner's detention was widely condemned by campaigners including former NBA star Dennis Rodman, who said he was planning to fly to Russia in a bid to free the US basketball player.
The Texan-born athlete revealed her fears that she could be in prison "forever" in a letter to President Biden on US Independence Day.
She wrote: "...As I sit here in a Russian prison, alone with my thoughts and without the protection of my wife, family, friends, Olympic jersey, or any accomplishments, I'm terrified I might be here forever.
"On the 4 July, our family normally honours the service of those who fought for our freedom, including my father who is a Vietnam war veteran.
"It hurts thinking about how I usually celebrate this day because freedom means something completely different to me this year."