(CNSNews.com) - "Well, we know that some of the detainees that have come out of Guantanamo have gone back to the fight, to the battlefield," Defense Secretary Chuck Hagel told reporters on Thursday. "We're aware of that."
Nevertheless, Hagel said he supports President Obama's intention to close the prison for enemy combatants:
"And we think that overall the policy of getting to close Guantanamo is clearly in the interests of the United States, as the president has articulated, which when I -- I was in the United States Senate, I supported it.
"It's an imperfect world," Hagel continued. "It's a dangerous world. This is why we pay so much attention to getting commitments from host countries...not to allow those detainees to go beyond what is required in order to secure them in these different host countries that take them. But we do know that some have joined the fight."
A reporter asked Hagel if the recidivism concerns him.
"Yes, of course it does," Hagel responded.
Appearing with Hagel, Joint Chiefs Chairman Gen. Martin Dempsey said he believes that the recidivism of Gitmo detainees is "a relatively small fraction of those detainees" who have been released to various countries that promise to keep them from returning to the battlefield.
"But even one would not make someone wearing the uniform very content," Dempsey said.
"So we -- I provide my advice in every case to the secretary of Defense who, as you know, is the certifying official. And the exact number is actually being assessed inside of the intelligence community, so I can't comment on that."
A number of Republicans sharply criticized Defense Secretary Hagel earlier this year when he approved the secret swap of five Taliban detainees being held at Gitmo for the release of Sgt. Bowe Bergdahl, a U.S. soldier suspected of walking away from his unit in Afghanistan.
Press reports say that as of October 2014, there were 149 detainees remaining at Guantanamo Bay, Cuba.
Fox News reported on Thursday that of the 620 detainees released over the years, 180 are believed to have returned to the battlefield; and as many as 20 to 30 of the them are believed to have joined ISIS and other terrorist groups inside Syria.
Fox News reported that Rep. Buck McKeon (R-Calif.), chairman of the House Armed Services Committee, wrote to Hagel on Thursday urging a suspension of detainee transfers, given "public reports that detainees are specifically rejoining the fight alongside ISIL."
"The U.S. Government must not release terrorist detainees at the same time we have committed U.S. service members to fight ISIL," McKeon wrote. "To continue to do so just as we have had to open a new front in the war on terror is unthinkable. Thus, I request an immediate suspension of all detainee transfers."
Speaking to Fox News's Greta Van Susteren Thursday evening, Sen. John McCain (R-Ariz.) said, "the eagerness with which this administration wants to get these people out of Guantanamo has clearly overridden good sense and a real concern for the lives of American men and women who are serving."
McCain said the freed detainees not only go back to the fight -- they attain leadership positions. "It's a red badge of courage. It's really a big deal that you were once in Guantanamo. That gives them leadership positions."
McCain said many lawmakers would agree to close Guantanamo if the administration had a plan, including a secure place to put the detainees.
"Basically, what his (Obama's) plan is, is to send them back to countries in the Middle East...The president wants to get rid of them in order to close Guantanamo. That's the overriding factor in his calculations, and it's disgraceful, because in the long run, it puts the lives of American men and women serving in the military in danger. It's a fact."
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