The United States has transferred 10 Yemeni detainees from Guantanamo Bay to the Gulf sultanate of Oman, the Pentagon announced on Thursday, bringing the military prison’s population below 100 for the first time since shortly after its opening in 2002.

In a statement, the Defense Department said the unusually large group transfer brings the number of inmates remaining to 93, a milestone or the Obama administration as it races to shut a prison that the president says has served as a recruiting tool for militants and undermined America’s reputation worldwide.

The Omani government, in a statement carried by a local news agency, said the Yemeni men, all of whom were held without charge for around 14 years,  had arrived for a temporary stay.

The detainees include Fahed Abdullah Ahmad Ghazi, who was 17 when he was brought to Guantanamo in 2002, according to the Center for Constitutional Rights (CCR), which advocates on behalf of Guantanamo detainees.

“There was never much doubt that Fahd’s imprisonment was unnecessary – he was cleared for release nearly a decade ago – yet he grew up at Guantánamo waiting for successive presidents to correct a glaring injustice,” Omar Farah, a lawyer for Ghazy, said in a statement release by CCR.

Because the Obama administration does not repatriate Yemeni prisoners, in part because of congressional restrictions and in part because of severe instability there, U.S. officials have had to scramble to find countries willing to take them. Yemenis have made up the single largest group at the prison.

The transfer brings to 14 the number of prisoners resettled out this year, indicating an accelerating effort to close Guantanamo before President Obama steps down in Jan. 2017.

“Sustained diplomatic engagement led us to this important milestone,” Lee Wolosky, the State Dept.’s special envoy for Guantanamo closure, said in a statement. “We expect to be in a position to empty Guantanamo of all detainees who are currently approved for transfer by this summer.”

But there are other prisoners who the White House hopes to place in U.S. detention facilities so they can undergo military trials or, for those who are deemed to dangerous too release but cannot be tried, so they can be detained indefinitely.

Rep. Mac Thornberry (R-TX), chairman of the House Armed Services Committee, said a rapid series of transfers “increases the danger” to the United States.

“The president’s tactic is try to get rid of everybody out there that he can, and then argue that there’s so few people there we might as well close it,” Thornberry said. “I think that’s exactly what’s going on.”

Karoun Demirjian contributed to this report.