WASHINGTON — The Pentagon on Thursday announced that it had transferred 10 lower-level Yemeni detainees from the Guantánamo Bayprison to Oman. The departure of the unusually large group of prisoners — each of whom spent about 14 years in custody — reduced the prison population to 93, the first time it has been in double digits since the Bush administration began bringing Afghanistan war prisoners to the naval base in January 2002.
The transfer, which took place on Wednesday, was the largest single resettlement of detainees in the yearslong effort to close the prison in Cuba. The 34 prisoners who are still on a list recommended for transfer if security conditions can be met in the receiving country may be moved by mid-2016, said Lee Wolosky, a State Department official who negotiates transfers.
Oman, which shares a border with Yemen, also took in 10 lower-level detainees in 2015. Its acceptance of 20 men over the past 13 months has significantly aided the Obama administration’s goal of repatriating or resettling all the men who have been recommended for transfer, most of whom have been languishing with that status since at least 2009 when a six-agency task force unanimously approved letting them go.
Secretary of Defense Ashton B. Carter, who approved the transfers, hailed them in a speech at a ceremony to hand over command of the United States Southern Command — which oversees Guantánamo — from Gen. John F. Kelly of the Marines to Adm. Kurt W. Tidd of the Navy. Mr. Carter noted that the detainee transfers amounted to “roughly 10 percent of the total remaining Gitmo population,” using a nickname for the naval base.
President Obama on Tuesday used his State of the Union address to reiterate his argument for closing the prison, which he says wastes taxpayer money and inflames anti-American sentiments.
But the Republican-controlled Congress has shown no appetite for lifting statutory impediments to Mr. Obama’s plan to bring the remaining detainees to a prison on American soil before he leaves office next year.
Senator Kelly Ayotte, Republican of New Hampshire, who opposes closing the Guantánamo prison and championed a provision in a law Mr. Obama signed late last year that bars repatriating detainees to Yemen, on Wednesday criticized the transfer of Yemeni detainees to Oman instead. Yemen is engulfed in a civil war and has an active affiliate of Al Qaeda.
Transfer deals typically involve arrangements to keep resettled detainees under surveillance and prevent them from traveling abroad. Without offering specific details, Ian Moss, chief of staff to Mr. Wolosky, said the negotiations with Oman included “measures that will be taken in order to sufficiently mitigate” any threat.
Both the Bush and Obama administrations had long hoped that Yemen would stabilize enough for dozens of lower-level Yemeni detainees to be repatriated. As a result, as lower-level detainees of other nationalities were repatriated or resettled over the years, their Yemeni equivalents remained in Guantánamo.
Finally, in November 2014, the Obama administration gave up on Yemen’s stabilizing soon, and struck diplomatic deals with other countries to resettle Yemeni men in small batches, starting with two Eastern European countries.
David Remes, an attorney who represents three of the detainees sent to Oman this week, said that country was a particularly good fit for them.
“I’m sure that they are ecstatic just leaving Guantánamo,” Mr. Remes said. “But it’s even better than that. They’ve been sent to Oman, an Arab country, whose language, culture and religion are their own. Oman is also one of Yemen’s neighbors, so their families will be able to visit them often.”
One of the three newly transferred men Mr. Remes represented, Muktar Yahya Najee al Warafi, drew attention last year when he filed a lawsuit asking a court to order the military to let him go because Mr. Obama had said the war in Afghanistan was over. A judge rejected the case.
The other nine Yemeni men transferred this week were Fahed Abdullah Ahmad Ghazi; Samir Naji al Hasan Moqbel; Waqas Mohammed Ali Awad;Abu Bakr Ibn Ali Muhhammad Alahdal; Abdul al Razzaq Muhammad Salih; Muhhammad Said Bin Salem; Said Muhammed Salih Hatim; Omer Saeed Salem al Daini; and Fahmi Abdullah Ahmed.