Overnight Defense: Yemen unrest challenges Obama's Gitmo plans

THE TOPLINE: Defense Secretary Chuck Hagel said Thursday that recent unrest in Yemen "has to be factored in" when deciding whether to release Yemeni detainees from the prison at Guantánamo Bay. "Because of what's happening in Yemen, and we were well aware of — of the danger and the uncertainty and what was going on in Yemen before today, that has to be factored in," he said at a Pentagon briefing. Yemen's prime minister, president and his cabinet abruptly resigned Thursday, after Shiite rebels known as the Houthis clashed with government forces in the capital of Sana'a and surrounded the presidential compound. The events have raised questions about whether Yemeni detainees, who make up the majority of Guantánamo’s prison population, should be released as part of President Obama's push to close the facility. Republicans in Congress have fought the release of the Yemeni detainees, warning they are likely to return to the battlefield and participate in plots against the Untied States. The country is a hotbed of al Qaeda activity. Hagel said Yemeni detainees — who number about 80 of the remaining population of 122 — have not been released back to Yemen, but to other countries willing to accept them. "It's what country is willing to host these detainees. We've not sent them back to Yemen," Hagel said. Hagel, as defense secretary, is personally responsible for signing off on detainee transfers, after an interagency certification process ensures countries receiving detainees are able and willing to monitor them and ensure they don't engage in future terrorist activities. The Pentagon chief said he personally signed off on the release of 44 detainees during his tenure. HAGEL QUESTIONS ISIS BODY COUNT: The Defense Secretary on Thursday downplayed claims that 6,000 fighters with the Islamic State in Iraq and Syria (ISIS) had been killed by U.S.-led airstrikes. Hagel also said body counts were not a significant metric to measure success in the war against ISIS. "I was in a war where there was a lot of body counts every day. And we lost that war," Hagel said at a Pentagon briefing  referring to the Vietnam War, when commanders touted the number of enemy killed as a measurement of success. Hagel said he had not seen "any verification" for the reported body count. "We do know that thousands of ISIL fighters have been killed, and we do know that some of ISIL's leadership have been killed," he said, using an alternate name for the group. His comments came after U.S. Ambassador to Iraq Stuart Jones said Thursday that coalition airstrikes against ISIS had killed more than 6,000 of the group's fighters. Jones also told Al Arabiya news network that airstrikes have "taken more than half" of the group's leadership. The U.S. has been striking ISIS targets in Iraq since August and in Syria since September. Jones's comments were the first time a U.S. official gave a public estimate on how many ISIS fighters were killed. Hagel said more important metrics are whether ISIS is on the defensive, having difficulty recruiting or accessing supplies, and able to communicate on the battlefield. CARTER TO PRESENT DOD BUDGET: Ashton Carter, President Obama’s nominee for Defense secretary, will defend the Pentagon’s fiscal 2016 budget request, said Senate Armed Services Chairman John McCain (R-Ariz.). "It’s going to be Carter, so we’re going to delay it some," he said, adding the panel wouldn’t convene on the budget blueprint until the first week of March. McCain had previously said he wanted current Defense Secretary Chuck Hagel to present the latest budget, which will roll out Feb. 2. However, McCain said, Hagel hinted he "didn’t want to." "That was his decision that he didn’t want to, and it’s fine if Ash Carter can get up to speed because he’ll be responsible" for it, McCain told reporters. With Carter’s nomination set to take place on Feb. 4, McCain’s comments indicate that Carter could be swiftly confirmed by the Senate next month. SYRIAN REBEL PROGRAM PANNED: Republicans on the Senate Armed Services Committee panned the administration’s effort to train Syrian rebels to take on ISIS. "It’s very weak and will not have significant impact," McCain said after a classified briefing on the program. "This strategy makes Pickett’s Charge look well thought out,” Sen. Lindsey Graham (R-S.C.) told reporters. He labeled the effort "immoral." "We’re about to train people for certain death," he said. The president proposed the train and equip effort last summer as an integral part of the strategy to defeat ISIS. Reportedly 400 U.S. trainers will be involved in the program with the goal of training roughly 5,000 rebels. Graham predicted the flow of recruits would also be impacted by conditions on the ground, as neighboring countries consider closing their borders to Syrian refugees. "Syria’s about to become beyond hell on earth," he said. IN CASE YOU MISSED IT: -Navy removes top commander at Gitmo -GOP lawmakers press administration to get tougher with Russia -Iraqi PM: Lower oil prices could impede ISIS fight -Dem senator wants Veterans’ hearing on 'Candy Land' -White House 'assessing' ouster of Yemen's president Please send tips and comments to Kristina Wong, kwong@thehill.com, and Martin Matishak, mmatishak@thehill.com. Follow us on  Twitter: @thehill,@kristina_wong, @martinmatishak