Chaos in Yemen is adding yet another challenge to President Barack Obama's drive to close the Guantanamo Bay prison, with administration officials saying a ban on detainee transfers to the unstable Middle East nation has effectively been restored.

Obama authorized detainee transfers to Yemen nearly two years ago amid high hopes that President Abed Rabbo Mansour Hadi's new leadership would help the U.S. fight terrorists operating from within his country's borders. But the transfer authority was never used, as a violent al-Qaida branch has thrived amid government instability that forced Hadi from office Thursday.

Administration officials, speaking on condition of anonymity because they were not authorized to speak on the record, said they are not considering sending any of the Yemenis at Guantanamo home for the foreseeable future amid the threat. They said that could change if conditions improve, but meanwhile, they are working aggressively to find third countries willing to take them.

The position is creating an additional hurdle in Obama's uphill effort to shutter the U.S. military prison for terrorism suspects in Cuba. Nearly two-thirds of the remaining 122 detainees are from Yemen, including 47 of the 54 who have been approved for transfer.

After languishing since 2010, Yemenis have started to move out of Guantanamo in the past two months. A dozen Yemenis have been sent to third countries since November, including last week's transfer of five to Oman and Estonia.

"While our policy preference is to repatriate detainees where we can do so consistent with our national security and humane treatment policies, we recognize that under certain circumstances the most viable transfer option is resettlement in a third country," said Ian Moss, who works on detainee transfers at the State Department. "We are actively working to identify appropriate transfer locations for every single detainee approved for transfer, and it may be the case that resettlement in a third country is the best option."

Republican senators introduced legislation last week to legally reinstate a ban on Yemeni transfers among other restrictions on Guantanamo transfers during Obama's remaining two years in office. They cited the recent shooting at the French satirical newspaper Charlie Hebdo and other attacks linked to al-Qaida in the Arabian Peninsula, which Washington considers to be the group's most dangerous branch.

"The last thing we should be doing is transferring detainees from Guantanamo to a country like Yemen," New Hampshire Republican Sen. Kelly Ayotte said during a news conference. "We have not received assurances from the administration that they will not seek to transfer anyone to Yemen, despite the wild, wild West nature of what we're facing when it comes to terrorism in Yemen."

Administration officials say even if they will not send detainees to Yemen now, Obama will not officially reinstate the ban to maintain flexibility in case conditions improve. The officials say he does not want any further restrictions on his ability to close Guantanamo with so little time left to meet his goal of shuttering it.

Obama suspended transfers to Yemen in January 2010 after a Nigerian man attempted to blow up a U.S.-bound flight on Christmas Day 2009 with explosives hidden in his underwear on instructions from al-Qaida operatives in Yemen. But in May 2013, the president announced he was lifting the Yemen ban as part of a renewed effort to close the prison after being blocked by Congress in his first term.