The Pentagon announced Monday that it had transferred another prisoner from Guantanamo Bay, bringing the prison population down to just 60 detainees.
Mohamedou Ould Slahi, who penned a memoir about his time in the military prison at the Guantanamo Bay Naval Base, Cuba, was released to his home country of Mauritania, the Defense Department said in a statement Monday.
"On July 14, 2016, a Periodic Review Board consisting of representatives from the Departments of Defense, Homeland Security, Justice, and State; the Joint Chiefs of Staff, and the Office of the Director of National Intelligence determined continued law of war detention of Slahi does not remain necessary to protect against a continuing significant threat to the security of the United States," the Pentagon said.
"As a result of that review, which examined a number of factors, including security issues, Slahi was recommended for transfer by consensus of the six departments and agencies comprising the Periodic Review Board," the Pentagon said.
According to a Department of Defense 2008 detainee assessment, Slahi was an admitted member of al Qaeda who took an "oath of allegiance" to Osama bin Laden. He was also assessed to have recruited three of the September 11, 2001, attackers and facilitated their training. Additionally, Slahi led Duisburg- and Montreal-based al Qaeda cells, the latter of which was responsible for the foiled "millennium" bomb attack on Los Angeles International Airport in 2000.
Slahi is known for writing the 2015 bestseller Guantanamo Diary about his years in detention.
"The United States coordinated with the Government of Mauritania to ensure this transfer took place consistent with appropriate security and humane treatment measures," the Pentagon said Monday.
The Obama administration has accelerated its transfer of Guantanamo detainees this year, as the president seeks to keep his campaign promise of shuttering the facility before he leaves office. Obama delivered his plan to close Guantanamo to Congress this year, proposing to transfer prisoners deemed too dangerous for release to stateside prisons.
Current law bars the transfer of Guantanamo prisoners to the United States.
The issue of Guantanamo has been a source of tension between lawmakers and the administration, as many Republicans have argued that it is in U.S. national security interests to keep the facility open. Obama, on the other hand, maintains that the prison undermines national security and is used as a recruitment tool for terrorists.
In August, the Pentagon announced the largest-ever prisoner release of 15 Guantanamo detainees, drawing ire from Republican lawmakers on a House intelligence panel who criticized the administration for endangering U.S. troops operating abroad.
Assessments from the director of national intelligence indicate that 30 percent of ex-Guantanamo detainees are confirmed to have resumed terrorist activities or are suspected of doing so.
The Guantanamo Bay prison population now stands at 60, down from a peak of about 800 during the George W. Bush administration.