President Barack Obama's pledge on Thursday to lift a ban on transfers of detainees to Yemen from the prison at Guantanamo Bay, Cuba, addresses one of the core obstacles to clearing out the detention camp.
Of the 86 detainees who have been cleared for transfer or release, 56 are from Yemen, where al Qaeda has a dangerous presence. There are 80 more prisoners who are not cleared and an unknown number of those are Yemeni as well.
Most of the Yemeni prisoners were captured more than a decade ago. Previously, they were a smaller percentage of the detainees, which included higher numbers of Afghans and Saudis.
But as the United States worked out agreements with other countries to transfer detainees to their homelands, it remained reluctant to do so with Yemen because of security concerns.
Repatriation of Yemeni prisoners was halted in 2010 after a man trained by militants in Yemen attempted to blow up a U.S.-bound plane in 2009 with a bomb concealed in his underwear.
The Obama administration so far has been skeptical that Yemen is stable enough to receive the transfers. Officials fear the consequences of a repatriated Yemeni eventually attacking the United States or its interests.
Yemen is home to an al Qaeda wing that was once described by Washington as the movement's most dangerous branch. Impoverished and turbulent, Yemen is located next door to the world's top oil exporter, Saudi Arabia, and major crude shipment routes.
Militants allied to al Qaeda in the Arabian Peninsula took advantage of Arab Spring chaos in Yemen in 2011 to seize control of some towns in the country's south. They were pushed from those towns last year but continue to fight government forces.
Recent developments, however, appear to have triggered reconsideration in Washington. Yemen's new president, Abd-Rabbu Mansour Hadi, has made tackling militants a top priority.
Supporters of shutting down Guantanamo said they were encouraged by Obama's pledge on transfers to Yemen but noted that he included heavy caveats during his wide-ranging speech on Thursday on how the United States will narrow its global war on terror.
When renewing his pledge to close Guantanamo, Obama said, "I am lifting the moratorium on detainee transfers to Yemen, so we can review them on a case by case basis. To the greatest extent possible, we will transfer detainees who have been cleared to go to other countries."
Wells Dixon, a senior attorney at the Center for Constitutional Rights, a New York organization that has represented a number of Guantanamo prisoners, said he was not encouraged by Obama's statements.
"While I welcome his lifting the ban on transfers to Yemen, and his renewed commitment to closing the prison, I am deeply troubled by his comment that cleared detainees will be released only 'to the extent possible,'" Dixon said.
"What does that mean? Are men going to be released and reunited with their families or not? If men are not released soon, especially to Yemen, the crisis at Guantanamo will worsen and men will die. They cannot be let down again; it's cruel and inhumane," he said.
Retired Rear Admiral Don Guter, who served as the judge advocate general and was the Navy's top judge on Sept. 11, 2001, praised the move to lift the ban on Yemeni transfers.
"That's really created paralysis on that issue so removing that moratorium is a great step," Guter said.
Mohammed Albasha, a spokesman for the Yemeni Embassy in Washington, said in a statement that the Yemeni government will work with the United States to ensure the safe return of detainees and work toward their rehabilitation.
TIMING OF TRANSFERS
Calls on Obama to close the Guantanamo Bay camp have risen as a hunger strike at the U.S. naval base in Cuba lingers. Prisoners are in the fourth month of their strike to protest the failure to resolve their fate after 11 years of detention.
More than 100 people have joined the protest and 32 have lost so much weight that they are being force-fed.
Transferring prisoners to Yemen was one of several steps Obama announced to move toward closing the prison.
Other moves included designating a site in the United States for military commissions, and including a new senior envoy at the State Department and Defense Department to oversee transfers.
Lifting the ban does not mean transfers to Yemen will immediately take place. Current law requires the Defense Department to certify for each transferred prisoner that the destination country is not a state sponsor of terrorism and would take action to make sure the individual would not threaten the United States.
Unless those provisions are removed or expire, they would have to be followed. No prisoners have been certified yet so it is not known how long the process takes.
Obama called on Congress to lift those and other restrictions that it placed on prisoner transfers starting in 2011. If it were so inclined, Congress could do this in the coming months as it works on defense legislation. The restrictions have had bipartisan support in the past.
The youngest of all the remaining Guantanamo prisoners is a Yemeni named Hassan Mohammed ali bin Attash, who is 26 or 27 and is an alleged al Qaeda member accused by the United States of being part of Osama bin Laden's security detail. He is not among those cleared for release or transfer; the United States wants to continue holding him indefinitely.
Some Republican reaction to Obama's speech showed it may be difficult for Obama to secure congressional support for lifting the restrictions on transfers.
"What's changed in Yemen?" asked Republican Senator Kelly Ayotte, who wants Guantanamo to stay open. "I think this issue of transferring to Yemen is very troubling, given the history we have with Yemen and terrorist activity there."