US President Barack Obama says he received security guarantees from Qatar over five Guantanamo Bay prisoners who were transferred to secure the release of a US soldier in Afghanistan.
US Army Sergeant Bowe Bergdahl, 28, was handed to US forces after being held for nearly five years by the Taliban.
He has left Afghanistan and is en route to a US military hospital in Germany.
Five Afghan detainees were released from the US prison in Cuba and handed to Qatar, which mediated the deal.
Sgt Bergdahl, who is said to be in good condition, was the only US soldier being held by the Taliban in Afghanistan.
His parents said they were "joyful and relieved" to hear of their son's release.
Hours after the release, President Obama told reporters the Qatari government had given the US assurances "that it will put in place measures to protect our national security".
He also thanked the Qatari authorities for their role in acting as a go-between during indirect US-Taliban negotiations that led to the deal.
Mother of freed US soldier Bowe Bergdahl, Jani Bergdahl speaks to the media, while his father Bob Bergdahl and President Obama look on. Photo: AFP
The exchanged prisoners are thought to be the most senior Afghans still held at Guantanamo. Under the deal, they will be banned from leaving Qatar for at least a year.
The Taliban said they welcomed their release with "great happiness".
"While Sgt Bergdahl was gone he was never forgotten," President Obama said, adding that the US had an "ironclad commitment" to bringing home its prisoners of war.
He was joined by Sgt Bergdahl's parents, Robert and Jani, at the White House on Saturday. They offered thanks to those who took part in securing their son's freedom.
In an emotional speech, Robert Bergdahl said his son was having trouble speaking English after his rescue.
The BBC reports the soldier is being taken to a US military medical centre in Germany, where he will receive medical treatment and begin the process of reconnecting with his family through telephone calls and video conferences.
