Washington (CNN)Defense Secretary Ash Carter says Pentagon teams are looking at U.S. sites to house detainees currently held at the Guantanamo Bay naval base as President Barack Obama's administration pushes to close the facility.
Ash Carter: Pentagon teams examining U.S. sites to house Guantanamo Bay detainees
The top two options, Carter said in a Thursday news conference, are military prisons in Fort Leavenworth, Kansas, and Charleston, South Carolina. He said assessment groups have already visited Fort Leavenworth and will soon travel to Charleston.
"This does not mean that either of these sites will be chosen; we will also be assessing other locations in coming weeks," Carter said.
"Ultimately, the facility surveys will provide me, the rest of the President's national security team and Congress with some of the information needed to chart a responsible way forward and a plan so that we can close the detention facility at Guantanamo and this chapter in our history once and for all," he said.
He said the 116 detainees currently being held at the facility fall into two categories: Those who can be transferred to other countries; and those who the United States must continue to hold.
Closing the military detention facility at the U.S. naval base on Cuba was among Obama's 2008 campaign pledges, but he's run into stiff opposition in Congress, particularly from Republicans who say moving terror suspects onto U.S. soil would pose unnecessary security risks.
In the same news conference, Carter acknowledged that the Pentagon is struggling to implement its train-and-equip program to help Syrian rebels who are combating ISIS, also known as ISIL, in the country.
"I've been candid that it is difficult and has been difficult with respect to Syria," Carter said.
He added that officials are "working on adjusting that program constantly, based upon the lessons we've learned so far, the experience we've had, to try to expand the numbers and the scope of that program. That's difficult work but it's necessary work."
Carter prodded Turkey to do more to assist in the fight against ISIS -- singling out the country's porous border with Syria and Iraq and saying the United States wants to see it controlled "more than it has been controlled over the last year."
"It is a border over which logistics for ISIL and fighters cross; and so we're looking for them to do more in that regard," Carter said, using another acronym for ISIS.
He also hit Russian President Vladimir Putin, calling him an "antagonist," when asked about several generals' recent remarks that his country -- not ISIS -- is the greatest threat to U.S. security.
Carter said the country "poses a existential threat to the United States by virtue simply of the size of the nuclear arsenal that it's had."
"Vladimir Putin's Russia behaves ... in some respects and in very important respects, as an antagonist," he said. "That is new. That is something, therefore, that we need to adjust to and counter."