WASHINGTON (AP) — The Pentagon said Monday it had transferred 11 Yemeni men to Oman this week after holding them for more than two decades without charge at the U.S. naval base in Guantanamo Bay, Cuba.

The transfer was the latest and biggest push by the Biden administration in its final weeks to clear Guantanamo of the last remaining detainees there who were never charged with a crime.

The latest release brings the total number of men detained at Guantanamo to 15. That's the fewest since 2002, when the George W. Bush administration turned Guantanamo into a detention site for the mostly Muslim men taken into custody around the world in what the U.S. called its “war on terror." The U.S. invasions of Afghanistan and Iraq and military and covert operations elsewhere followed the Sept. 11, 2001, al-Qaida attacks.

The men in the latest transfer included Shaqawi al Hajj, who had undergone repeated hunger strikes and hospitalizations at Guantanamo to protest his 21 years in prison, preceded by two years of detention and torture in CIA custody, according to the U.S.-based Center for Constitutional Rights.

Rights groups and some lawmakers have pushed successive U.S. administrations to close Guantanamo or, failing that, release all those detainees never charged with a crime. Guantanamo held about 800 detainees at its peak.

The Biden administration and administrations before it said they were working on lining up suitable countries willing to take those never-charged detainees. Many of those stuck at Guantanamo were from Yemen, a country split by war and dominated by the Iran-allied Houthi militant group.

The transfer announced Monday leaves six never-charged men still being held at Guantanamo, two convicted and sentenced inmates, and seven others charged with the 2001 attacks, the 2000 bombing of the USS Cole, and 2002 bombings in Bali.