A former U.S. Marine held captive in Russia has been freed as part of a rare prisoner exchange, an unexpected development amid the war in Ukraine.

On Wednesday, the U.S. government announced it had secured the release of ex-Marine Trevor Reed, who has been held in a Russian prison since 2019. He was arrested for allegedly assaulting police officers after getting intoxicated at a party he attended with his Russian girlfriend.

Reed’s health while in prison was reportedly declining and the U.S. embassy in Moscow was limited in its access to him, increasing the pressure on the Biden administration to secure his release while simultaneously imposing sanctions on Moscow for its actions in Ukraine.

President Joe Biden welcomed Reed's release in a statement shared by the White House and acknowledged the difficult diplomacy it took to secure his return home. "The negotiations that allowed us to bring Trevor home required difficult decisions that I do not take lightly," Biden said in the statement.

Biden had come under sustained pressure from Reed’s parents, who have publicly urged him since his inauguration to make rescuing their son a priority in his dealings with Russia. His parents went so far as to wait along the route of Biden's motorcade during a visit to Fort Worth, Texas in March, a move that helped facilitate a phone call between them and the president.

After the news of Reed’s release was revealed, his parents thanked Biden for “his kindness, his consideration, and for making the decision to bring Trevor home,” adding that it may have saved their son’s life as his health deteriorated.

To bring Reed home, the U.S. agreed to trade him for a convicted Russian drug trafficker named Konstantin Yaroshenko. Arrested in 2011 on an international arrest warrant, Yaroshenko was sentenced to 20 years in prison on charges of planning to distribute cocaine in the U.S.

Russia has vehemently protested against U.S. law enforcement arresting its citizens, including those who are accused hackers or arms traffickers.

It remains unclear in which third country the exchange took place. Open source analysts pinpointed a jet owned by Russian intelligence landing in Ankara, Turkey in the hours leading up to the announcement, but the exact time and location of the swap has yet to be confirmed.