Defense Secretary Jim Mattis said Tuesday that allied countries of origin should take custody of ISIS foreign fighters captured in Syria rather than sending them to Guantanamo Bay, as proposed under a new policy announced by President Donald Trump.
"Doing nothing is not an option," Mattis said following a conference of defense ministers in Rome on the issue that has taken on urgency with the capture of thousands of Islamic State of Iraq and Syria (ISIS) fighter suspects by the U.S.-backed Syrian Democratic Forces (SDF).
Mattis told reporters traveling with him that "The important thing is that the countries of origin keep responsibility for them. How they carry out that responsibility, there's a dozen diplomatic, legal or whatever ways."
"But the bottom line is, we don't want them going back on the street," said Mattis, who was on a week-long trip for meetings with coalition and NATO partners in Rome, Brussels, Stuttgart and Munich.
Mattis declined comment on whether the U.S. would take custody of the prisoners with Guantanamo as an option, although U.S. military and intelligence officials have interrogated many of them.
"We want to make certain that foreign fighters are taken off the battlefield and they don't show up someplace else -- right now I want to hold with that," he said. The priority, he said, was to "define the problem and then we'll get the solution."
An accurate count of the detainees that included their countries of origin was necessary before any decisions could be made on where they should be sent, Mattis said.
There are no known Americans among the detainees, but a U.S. citizen who surrendered to the SDF in Syria is being held in Iraq amid a protracted legal fight over his fate.
Trump has announced that "Gitmo" was open to new prisoners, but the Pentagon appeared to prefer having them sent anyplace else but the detention facility at the U.S. naval base in Cuba.
A senior Pentagon official traveling with Mattis told reporters that that prisoners captured on the battlefields of Syria, Iraq and Afghanistan should be sent to face justice in their home countries.
"We are working with the coalition on foreign fighter detainees, and generally expect these detainees to return to their country of origin for disposition," said Katie Wheelbarger, the principal deputy assistant secretary of Defense for International Security Affairs, Reuters reported.
Wheelbarger made the remarks Sunday after Mattis briefed reporters on a range of issues that will dominate his meetings in Europe.
The Pentagon's position was in contrast to the policy announced by Trump in his State of the Union Address last month.
Trump said he had signed an executive order shortly before the address to a joint session of Congress directing Mattis "to re-examine our military detention policy and to keep open the detention facilities in Guantanamo Bay."
"Terrorists who do things like place bombs in civilian hospitals are evil. When possible, we have no choice but to annihilate them. When necessary, we must be able to detain and question them," Trump said.
"But we must be clear: Terrorists are not merely criminals, they are unlawful enemy combatants," Trump said.
In a departure from his prepared remarks, Trump said "I am asking Congress to ensure that in the fight against ISIS and al-Qaida we continue to have all necessary power to detain terrorists wherever we chase them down, wherever we find them. And In many cases for them it will now be Guantánamo Bay."
Trump said that many of the prisoners who were once in the custody of the U.S. at Guantanamo Bay and other facilities have returned to the battlefield. He specifically cited Abu Bakr al-Baghdadi, the ISIS leader, who was once held at a U.S. jail in Iraq.
Trump's announcement was a major reversal of the policy of former President Barack Obama, who had pledged to close "Gitmo" but was blocked by Congress.
In the administration of former President George W. Bush, the Guantanamo Bay prisoner population grew to more than 700 but had dropped to 242 when Obama took office.
Currently, there are 41 prisoners at the detention facility. A total of about 1,700 uniformed personnel and contractors maintain the facility.
Five of the 41 prisoners have been approved for release or resettlement by Bush or Obama administration review boards, but the State Department has withheld final approval.
On Monday, Rear Adm. Edward Cashman, commander of the detention facility, said he had yet to receive any "military operational orders" on implementing Trump's "policy guidance," the Miami Herald reported from Guantanamo Bay.
The legal and humanitarian problems posed by the presence of prisoners accused of fighting for ISIS were most acute in Syria. Upwards of 1,000 are believed to be held there, mostly by the Kurdish-led SDF which last year retook Raqaa, the so-called ISIS capital.
Aboard Mattis' plane, Wheelbarger said that at one point the SDF was capturing ISIS fighters at the rate of 40 per day.
"The capacity problem is very real" at the makeshift jails used by the SDF, Wheelbarger said, but "I think they are willing to hold them as long as we need."
"If they continue to capture them at the rates that they are, their facilities are eventually going to be full," she said.
"These aren't necessarily the best detention facilities in the sense of they are being held in Syria and not in the most secure area," Wheelbarger said. "I think it would be better if we make sure they are prosecuted if possible in their countries of origin."
Last week, the SDF announced the capture of two British citizens -- El Shafee Elsheikh and Alexanda Amon Kotey -- who were originally part of a notorious group of four foreign fighters that the British tabloids dubbed the "Beatles."
The other two members of the group have been killed in targeted coalition operations.
The "Beatles" participated in gruesome beheading videos and were believed responsible for the executions of American journalists James Foley and Steven Sotloff, and American aid worker Peter Kassig.
-- Richard Sisk can be reached at Richard.Sisk@Military.com.