The Pentagon says that 15 Guantanamo Bay detainees have been transferred to the United Arab Emirates, the largest transfer under the Obama administration.
A US Department of State official, who spoke on condition of anonymity, said Monday that 12 of the men are Yeminis and the other three are Afghans.
The transfer brings to 61 the population of inmates in the facility, where about 780 inmates have been imprisoned since the September 11, 2001 attacks.
"The United States is grateful to the government of the United Arab Emirates for its humanitarian gesture and willingness to support ongoing US efforts to close" Guantanamo, the Pentagon said in a statement on Monday.
The Pentagon has had difficulty finding a third country to take Yemeni detainees as they cannot go home due to the Saudi aggression against the country.
The former detainees, once transferred, are usually freed as long as they are being supervised and undergo rehabilitation programs.
Amnesty International USA welcomed the move, saying it is a sign President Barack Obama is serious about closing the controversial facility before he leaves office.
"It's a significant repudiation of the idea that Guantanamo is going to be open for business for the indefinite future," Naureen Shah, Amnesty International USA's security and human rights program director, told AFP.
"The continued operation of the detention facility weakens our national security by draining resources, damaging our relationships with key allies and partners, and emboldening violent extremists," Ambassador Lee Wolosky, the special envoy for Guantanamo closure, said in a statement.
On February 23, Obama presented a long-awaited plan to close the US-run military prison in Cuba.
Obama had initially promised to close the prison during the 2008 presidential election campaign, citing its damage to the US reputation abroad.
However, the president backed away on his campaign promise later on due to stiff opposition from Congress.