The Pentagon cannot account for more than $500 million in military aid given to Yemen, The Washington Post reports. Members of Congress have been pressing Defense Department officials about the fate of the untracked supplies in a country that has been in a state of chaos since Shiite Houthi rebels overthrew the government in January. (The U.S. closed its embassy in Sanaa last month.) There are fears that everything from M-16s to Humvees may have fallen into the hands of al Qaeda- or Iranian-backed rebels. “We have to assume it’s completely compromised and gone,” a Capitol Hill aide said.