Fifteen prisoners at the Guantanamo Bay detention center were sent to the United Arab Emirates in the single largest release of detainees during the Obama administration, the Pentagon announced Monday.

The transfer of 12 Yemeni nationals and three Afghans to the UAE comes amid a renewed push to whittle down the number of detainees held at the U.S. prison in Cuba that President Barack Obama wants to close.

The Pentagon says 61 detainees now remain at Guantanamo, which was opened in January 2002 to hold foreign fighters suspected of links to the Taliban or the Al Qaeda terrorist organization. During the Bush administration, 532 prisoners were released from Guantanamo, often in large groups to Afghanistan and Saudi Arabia.

The latest batch of released prisoners had mostly been held without charge for some 14 years at Guantanamo. They were cleared for release by the Periodic Review Board, comprised of representatives from six U.S. government agencies.

The UAE successfully resettled five detainees transferred there last year, according to the Pentagon