Defense Secretary Chuck Hagel told lawmakers Wednesday that last month's prisoner swap with the Taliban may have been the "last, best" chance to secure the release of Sgt. Bowe Bergdahl, the only U.S. soldier held captive in Afghanistan. He said mediators indicated time was slipping away to get Bergdahl out safely.

Hagel, the first Obama administration official to testify publicly about the controversial deal, told the House Armed Services Committee that Qatari officials warned in the days before the exchange that "time was not on our side" and a leak would sabotage the deal. The transfer of five detainees at the U.S. prison in Guantanamo Bay, Cuba, to Qatar was legal and advanced national interests, he added.

Republicans and some Democrats have sharply criticized the administration for not informing Congress in advance, with some accusing the president of breaking a law requiring 30-day notification of any Guantanamo prisoner release. Other questions center on whether Bergdahl deserted and whether the U.S. gave up too much for his freedom. Administration officials have told Congress that four of the five Taliban officials will likely rejoin the fight.

"We could have done a better job of keeping you informed," Hagel acknowledged to the panel. But he called the operation an "extraordinary situation" that combined time-sensitive concerns over Bergdahl's health and safety, last-minute arrangements over where to pick up the soldier and persistent fears the Taliban may have been negotiating in bad faith.

"We grew increasingly concerned that any delay, or any leaks, could derail the deal and further endanger Sgt. Bergdahl," Hagel said. "We were told by the Qataris that a leak would end the negotiations for Bergdahl's release. We also knew that he would be extremely vulnerable during any movement, and our military personnel conducting the handoff would be exposed to a possible ambush or other deadly scenarios in very dangerous territory."

Read more at the Associated Press