Defense Secretary Chuck Hagel said he takes his role in the decision to release Sgt. Bowe Bergdahl in exchange for five Taliban leaders “damn seriously” and stood by it, saying it was the “last, best opportunity to free him” and was both legal and in the national interest.

Hagel clarified that President Obama made the final decision on a “tough call” and he supported it, and said he has "seen no evidence that directly links any American combat death to the rescue or finding or search for" Bergdahl.

"I have asked the questions -- we have all asked the questions. I have seen no evidence, no facts presented to me," he told the House Armed Services Committee.

The negotiations involved in the Bergdahl swap and commitments from Qatar, he said, led him to the conclusion that the risks the Taliban leaders posed to the United States “were substantially mitigated.”

He said the president's entire national security team unanimously agreed, and he stressed that administration officials did not know if they were going to release the Taliban leaders until they had Bergdahl in hand.

“War is a dirty business, and we don't like to deal with those realities – but realities they are,” he said.

Republicans weren't satisfied by his explanations and expressed outrage about the administration's decision not to notify Congress as required by law and engage in what they consider to be negotiations with terrorists.

Rep. Buck McKeon, the chairman of the House Armed Services Committee, said there is now a breach of trust between Congress and the administration on national security matters.

At one point, McKeon accused the administration of not notifying Congress because they knew that key lawmakers had opposed the deal when it was first raised in 2011.

Hagel at times asserted that the administration did not negotiate with terrorists over the Bergdahl release because the Qatari government was acting as an intermediary – to which Rep. Mike Turner, R-Ohio, replied: “So the new policy of this administration is that we don't negotiate directly with terrorists?”

After that heated exchange, Rep. Jim Cooper, D-Tenn., took issue with the “prosecutorial tone” of the hearing, referring to Turner, he said he didn't know if “my friend on the other side of the aisle is already running for majority leader or not” – a reference to Tuesday night's primary defeat of House Majority Leader Eric Cantor, R-Va., and the GOP scramble for the leadership post.

Rep. Jeff Miller, R-Fla., asked if the administration would interpret the Congressional notification law the same way again on another detainee transfer.

“Not unless there's an extraordinary set of circumstances like this one,” Hagel replied.