Members of a militia group loyal to Yemen's President Abed Rabbo Mansour Hadi, known as the Popular Committees, chew qat as they sit next to their tank, guarding a major intersection in Aden, Yemen, in this March 21, 2015, file photo. Once hailed by President Barack Obama as a model for fighting extremism, the U.S. counterterrorism strategy in Yemen has all but collapsed as the country descends into chaos, according to U.S. and Yemeni officials. (AP Photo/Hamza Hendawi, File)