KABUL - US Defence Secretary Chuck Hagel said on Sunday that an operation to free soldier Bowe Bergdahl in exchange for Taleban prisoners was undertaken to save his life, as the insurgents' leader hailed the swap as a "big victory".
Bergdahl, the only US soldier captured by the Taleban since the war began in 2001, was freed after almost five years in captivity in exchange for five senior insurgents who had been detained at the US military prison in Guantanamo Bay.
Both parties claimed success for the dramatic deal, which was brokered by Qatar.
Hagel even suggested it could provide a breakthrough for peace in Afghanistan.
But the swap was criticised by Republican lawmakers, who demanded to know whether the Taleban prisoners would return to fighting the United States and questioned whether other Americans abroad would be at risk.
Hagel provided new details on the operation to free the 28-year-old Bergdahl to reporters while en route to Bagram air base north of Kabul, where he paid a brief, unannounced visit to meet with more than a dozen members of the team that retrieved Bergdahl.
"We believed that the information we had, the intelligence we had, was such that Sergeant Bergdahl's safety and health were both in jeopardy, and particularly his health deteriorating," Hagel said, according to a Pentagon transcript.
"It was our judgement that if we could find an opening and move very quickly with that opening, that we needed to get him out of there, essentially to save his life."
Dozens of US special forces troops backed up by helicopters were sent to an undisclosed location in eastern Afghanistan where Taleban militants handed over Bergdahl, defence officials have said.
"Fortunately, no shots were fired," Hagel explained.
"There was no violence. It went as well as we not only had expected and planned, but I think as well as it could have."
In an interview with NBC's "Meet the Press" from Bagram, Hagel said the prisoner trade could provide a window of opportunity for peace in Afghanistan.
"Maybe this will be a new opening that can produce an agreement," he said, noting that the United States had engaged in talks with the Taleban in the past.
Mullah Mohammad Omar, the spiritual leader of the Taliban, issued a rare statement praising the release of the five Guantanamo detainees as a "big victory," in what some saw as a potential confidence-building measure.
Bergdahl's release came four days after President Barack Obama announced a timetable for a final US pullout by end-2016.