As far as Tom Cotton is concerned, Guantanamo detainees can "rot in hell."

That's how the freshman Republican senator from Arkansas responded Thursday morning to testimony by Principal Deputy Undersecretary of Defense for Policy Brian McKeon, who said the detention facility has become a recruitment tool for terrorists, is hugely expensive to operate, and needs to be shut down. Doing so, McKeon said, is a "national security imperative" for the Obama administration.

"In my opinion, the only problem with Guantanamo Bay is there are too many empty beds and cells there right now," Cotton, an Iraqi war vet, said during a contentious Senate Armed Services Committee hearing on the future of Guantanamo and US detention policy. "We should be sending more terrorists there. As far as I'm concerned, every last one of them can rot in hell. But as long as they can't do that, they can rot in Guantanamo Bay."

The hearing was briefly interrupted by about a dozen CodePink protesters who wore t-shirts that said "Shut Down GITMO" and orange jumpsuits, symbolic of the attire many Guantanamo detainees donned when they were rendered to the remote naval base in Cuba 13 years ago.

The Islamic State has forced its hostages to wear the same jumpsuits, which McKeon said is "no coincidence," underscoring his point that Guantanamo is being used to "incite local populations."

Senator Tom Cotton at Tuesday's Armed Services Committee hearing

"It is no coincidence that the recent ISIS videos showing the barbaric burning of a Jordanian pilot and the savage execution of a Japanese hostage each showed the victim clothed in an orange jumpsuit, believed by many to be the symbol of the Guantanamo detention facility," McKeon said.

Since last November, the Obama administration has transferred 27 detainees to nine different countries. Of the 122 detainees who continue to be held captive, 54 have been cleared for release. But lawmakers are determined to put an end to any additional transfers.

Last month, four Republican senators — Kelly Ayotte, Lindsay Graham, John McCain, and Richard Burr — unveiled the Detaining Terrorists to Protect America Act of 2015, legislation that would place a two-year moratorium on the transfer of Guantanamo detainees who the military deemed to be of medium and high risks at the time of their capture, effectively scuttling President Barack Obama's goal of shuttering Guantanamo before he leaves office.

Graham is opposed to closing Guantanamo because he thinks it should still be used as a detention and interrogation center. An aide to Graham told VICE News last month that the senator is concerned about the administration's ability to collect actionable intelligence when it captures a terrorism suspect.

"Basically anytime we capture a terror suspect nowadays, we hold them for a very limited amount of time, try to get information — which we may or may not get under the time constraints — and then Mirandize them, telling them they have the right to remain silent," the aide said. "Senator Graham believes we should hold these types of suspects as enemy combatants, which allows humane, lawful interrogation for an unlimited amount of time. Then if you want to, at some point in the future, they can be turned over for trial in federal district court.

"As for detention, when we capture a terror suspect today we don't have any place to long-term detain them. President Obama isn't using Gitmo anymore. But if we do capture a terror suspect, where are we going to put him? Putting them in jail is fine, but the point is to gather intelligence to stop future attacks or plots."

McCain said he too is troubled that "our nation continues to lack a clear policy to detain and humanely interrogate terrorist detainees for the purpose of intelligence gathering in what is a rapidly expanding conflict against violent extremist enemies."

McKeon was questioned about the administration's future detention policy. He said where and how to detain and interrogate a suspected terrorist captured in the future "will be handled on a case-by-case basis and by a process that is principled, credible, and sustainable…. The President has made clear that we will not add to the population of the detention center at Guantanamo Bay."

Next week, the Armed Services Committee, chaired by McCain, will take up the legislation, which McKeon said Obama opposes. McCain had been Obama's strongest Republican ally on closing Guantanamo. As recently as December, he said he supports the administration's goal. But McCain said Tuesday that until the White House comes up with a plan for what it intends to do with detainees it cannot prosecute and who are too dangerous to release, he objects to plans to empty the detention facility.

"For many years, I have believed that it would further U.S. national security interests to close the Guantanamo detention facility. I still do," McCain said Tuesday. "The problem is that, for more than six years now, the Obama Administration has offered no comprehensive plan to responsibly close the Guantanamo detention facility ... What we now have instead is the perception of a President rushing to fulfill a political promise."

McKeon said the White House does have a plan: prosecuting some high-value detainees, such as self-professed 9/11 mastermind Khalid Sheikh Mohammed, before military commissions; having a parole board review the cases of so-called "forever prisoners," those who were not previously cleared for release; and incarcerating and prosecuting the remaining men in the United States, a move opposed by Republicans and many Democrats.

"We understand that such transfers are currently barred by statute," McKeon said. "As a result, the government is prohibited from prosecuting any detainees in the United States, even if it represents the best — or only — option for bringing a detainee to justice…. We understand we need to work with Congress on this, and I pledge to you we will do so."

Much of the recent ire revolving around the administration's plans to close Guantanamo is due to the secret swap that took place last May of five Taliban detainees in exchange for Army Sergeant Bowe Bergdahl, a prisoner of war who was held in captivity by militants for five years.

The Government Accountability Office (GAO) said in a report last August that the prisoner swap, which cost $1 million, was illegal and that the Obama administration violated a provision in a defense bill restricting the use of funds for the transfer of Guantanamo detainees unless Congress receives 30 days' written notice.

Now, an unconfirmed report claims that one of the Taliban Five — they were transferred to Qatar — has "returned to the fight." Cotton said he and other Republican lawmakers sent Secretary of Defense Chuck Hagel a classified letter last December inquiring about the Taliban Five but they have yet to receive a response. McKeon did not address the specific allegations, other than to say that none of the Taliban Five "returned to the battlefield." He said when detainees are released from Guantanamo the administration seeks assurances from foreign governments that detainees' travel will be restricted, and that they will be monitored and enter a rehabilitation program for jihadists.

"The decision to transfer is made only after detailed, specific conversations with the receiving country about the potential threat a detainee may pose after transfer and the agreement about the measures the receiving country will take in order to sufficiently mitigate that potential threat," McKeon said, adding that there would not be any detainee transfers to Yemen due to both government instability there and the presence of al Qaeda. The vast majority of cleared detainees are Yemenis. "We also review the capability of the receiving country and its security establishment, and its track record in adhering to prior agreements in this regard."

The Defense Department official would not disclose the specific security measures the administration receives from foreign governments because that information is classified, something that Ayotte and McCain said their proposed legislation aims to change by forcing the Obama administration to declassify the security assurances on detainee transfers.

As for fears that released Guantanamo detainees have re-engaged in terrorism, Nicholas Rasmussen, the director of the National Counterterrorism Center, testified to the committee and cited new recidivism figures, shooting down numbers that Ayotte and her colleagues have quoted. He said as of last September, 107, or 17.3 percent, of the 620 detainees who have been released from Guantanamo are "confirmed of re-engagement in terrorist or insurgent activities." Rasmussen said 77 former detainees, or 12.4 percent, "were suspected of reengagement." All of those detainees were released by the Bush administration.

Of the 88 detainees transferred during Obama's tenure, "6 or 6.8 percent were confirmed of re-engagement in terrorist or insurgent activities, and 1 or 1.1 percent was suspected." Rasmussen said the government would issue another unclassified recidivism report in March.

How the intelligence community determines whether a detainee has re-engaged in terrorism or is suspected of re-engagement is shrouded in secrecy. But Rasmussen noted that "anti-US statements or propaganda" does not qualify as terrorist or insurgent activity, and he said some former detainees have been added to the "suspected list" and "later removed after information came to light suggesting that the individual had not re-engaged after all."

Human rights and civil liberties groups have condemned Republicans for using fear to keep Guantanamo open and deprive detainees due process.

"Senators Kelly Ayotte, Richard Burr, Lindsey Graham, and John McCain apparently deem keeping Guantanamo open as an internationally recognized symbol of torture and lawlessness a price worth paying in order to achieve their higher objective of undermining Obama's legacy," the Center for Constitutional Rights, whose attorneys represent dozens of detainees, said in a statement. "When maintaining the current momentum of transfers is a moral imperative and national security priority, it is shameful to draw upon fears about recent events to push a bill that at its core is nothing other than a craven attempt to score partisan political points."

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