Soldiers at the sprawling Bagram Airfield, the main hub for US forces in Afghanistan, were surprised to learn when they woke on Sunday that Bergdahl had been treated at their base's hospital and was free of his captors.

Staff Sergeant Robert Mashburn, 28, heard the news from his wife in a Skype phone call.

"My wife told me that a soldier had been freed and I knew who it was,"said Mashburn, a member of the 101st Airborne.

That Bergdahl's release came at a price, with five senior Taliban figures allowed to leave the US prison in Guantanamo Bay, Cuba, posed a difficult dilemma, he said.

"Letting them (Taliban militants) go, I don't want to see that happen. At the same time, I would do anything for that soldier, " he said. (snip)

"Whatever your beliefs, if you think we should be here or we shouldn't be here, we have someone, an American, in captivity and we've got to get him. I think everyone can agree on that," he said.

Two Republican lawmakers on Saturday accused President Barack Obama of breaking the law by approving the release of five Afghan detainees held at Guantanamo Bay, Cuba, in exchange for a U.S. soldier believed held by Islamist insurgents for five years.

The White House agreed that actions were taken in spite of legal requirements and cited "unique and exigent circumstances" as justification.

In comments on Sunday morning news programs, Republicans were unanimous in saying the deal would embolden U.S. enemies to take other Americans hostage and that Obama had violated the law that requires that Congress be notified 30 days in advance of any release of Guantánamo detainees.

Obama advisers fired back by saying Republicans would be in full attack mode if the U.S. government had squandered an opportunity to gain Bergdahl’s release.

Speaking to reporters traveling with him in Asia, Hagel also left open the possibility that the circumstances of Bergdahl’s capture might one day be investigated, but said that was not the Pentagon’s first priority. Bergdahl was first noticed missing from his base in Afghanistan June 30, 2009, amid allegations that he left the base voluntarily.

“Sgt. Bergdahl is a member of the United States Army,” Hagel said. “He's a sergeant in the United States Army. Our first priority is assuring his well-being and his health and getting him reunited with his family. Other circumstances that may develop and questions, those will be dealt with later.”

Sen. Ted Cruz, a Texas Republican and possible 2016 presidential candidate, said the United States had paid “a very dangerous price” for Bergdahl’s freedom.

“I do not think the way to deal with terrorists is through releasing other violent terrorists,” Cruz told ABC’s “This Week” program.

Suggesting that the United States could have used military force to rescue Bergdahl, Cruz said: “The reason why the U.S. has had the policy of not negotiating with terrorists is because once you start doing it, every other terrorist has an incentive to capture more soldiers.”

The Democratic-controlled United States Congress issued its own report on November 18, 1987, stating that "If the president did not know what his national security advisers were doing, he should have". The congressional report wrote that the president bore "ultimate responsibility" for wrongdoing by his aides, and his administration exhibited "secrecy, deception and disdain for the law". It also read that "the central remaining question is the role of the President in the Iran–Contra affair. On this critical point, the shredding of documents by Poindexter, North and others, and the death of Casey, leave the record incomplete".