The transfer of prisoners out of Guantanamo Bay has ground to a halt amid a slow Pentagon approval process.
That's caused frustration within the administration and raised doubts that President Barack Obama can fulfill his campaign promise to close the prison at the US Navy base in Cuba for terrorism suspects.
A detainee sent back to Algeria in March is the only prisoner to have moved out this year, beyond the exchange of five Taliban members in return for US Army Sgt Bowe Bergdahl, taken prisoner in Afghanistan.
The slow pace is the result of a law giving Defense Secretary Chuck Hagel final authority to transfer detainees. Pentagon officials say they must consider the risks before signing off.
The White House says recidivism risks must be weighed against the danger to the US in keeping the prison open.
