The US military prison in Guantanamo Bay should be shut down before President Barack Obama leaves office, Pentagon chief Ashton Carter has said, calling the facility a "rallying cry for jihadi propaganda".
He said the Department of Defense was actively searching for an alternative detention facility.
"This is not something, in my judgment, that we should leave to the next president," Mr Carter told reporters at the Pentagon on Thursday.
He said he and the White House were on the same page when it came to closing the prison, as Obama promised to do before being elected and which he is now making a final push to accomplish.
"As long as this detention facility remains open, it will remain a rallying cry for jihadi propaganda," Carter said.
"It's expensive ... and not something the president wants to leave to his successor."
He said defence officials had been assessing Fort Leavenworth, in Kansas, and the Navy Brig in Charleston, South Carolina, as possible destinations for prisoners.
"We will also be assessing other sites in the coming weeks," he added.
Any transfers of prisoners to sites within the continental United States are likely to be highly controversial in Congress, but Carter said his department is working on putting together a concrete plan for politicians to consider.
"Our responsibility is to provide [Congress] with a plan that they can consider that is a responsible one so that people ... can make up their minds," he said.