Six men long held at Guantanamo Bay arrived Saturday in Oman, the first movement of detainees out of the U.S. prison for terrorism suspects in five months as Congress considers new restrictions on transfers.

The six detainees — all from Oman's war-torn Mideast neighbor Yemen — boarded a flight from the U.S. prison in Cuba on Friday, bringing Guantanamo's population down to 116. The move means President Barack Obama has now transferred more than half of the 242 detainees who were at Guantanamo when he was sworn into office after campaigning to close it.

Yet Obama remains far from achieving his closure goal, with just a year and a half left in office, final transfer approvals coming slowly from the Pentagon and lawmakers threatening to make movement out even harder. The transfers to Oman are the first to be given final approval by Defense Secretary Ash Carter, who has been on the job four months.

The six new transfers include Emad Abdullah Hassan, who has been on hunger strikes since 2007 in protest of his confinement without charge since 2002. In court filings protesting force-feeding practices, Hassan said detainees have been force-fed up to a gallon at a time of nutrient and water.

The five other detainees sent to Oman were identified by the Pentagon as Idris Ahmad 'Abd Al Qadir Idris, Sharaf Ahmad Muhammad Mas'ud, Jalal Salam Awad Awad, Saa'd Nasser Moqbil Al Azani and Muhammad Ali Salem Al Zarnuki

"The United States is grateful to the Government of Oman for its humanitarian gesture and willingness to support ongoing U.S. efforts to close the Guantanamo Bay detention facility," the Defense Department said in a statement announcing the transfer. "The United States coordinated with the Government of Oman to ensure these transfers took place consistent with appropriate security and humane treatment measures."

The 11 detainees transferred so far in 2015 have all been from Yemen. Forty-three of the 51 remaining detainees who have been approved for transfer are from Yemen. The Obama administration won't send them home due to instability in Yemen and has been looking for other nations willing to accept them.

"We are working feverishly to transfer each of the 51 detainees currently approved for transfer," said Ian Moss, who works on detainee transfers at the State Department. "It is not in our national security interest to continue to detain individuals if we as a government have determined that they can be transferred from Guantanamo responsibly."

Some lawmakers want to impose stiffer requirements for transferring Guantanamo detainees to other countries. Obama has threatened to veto a House bill in part because of the Guantanamo restrictions.

An administration official said Oman agreed to accept the six Yemeni detainees about a year ago. But the defense secretary must give final approval to the move, and that has been a slow process at the Pentagon.

The administration official, speaking on a condition of anonymity without authorization to go on the record, said the Pentagon has sent no further transfer notification to Congress, which is required 30 days before detainees can be moved.

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