A tweet from Donald Trump appears to have accidentally revealed that a U.S. Navy SEAL team was deployed to Iraq. The president secretly traveled to the country to meet with American forces serving in a combat zone—the first time since he was elected to office. A video posted Wednesday on the president’s Twitter account didn’t blur the faces of special-operations forces, as is usual practice. Defense Department officials told Newsweek that information concerning which units are deployed and where is almost always classified and is a violation of operational security. In the video, the president and the first lady pose for pictures with service members that appear to be from SEAL Team Five. “Revealing them casually, through an unusual media exposure even if it’s the commander in chief, would prove a propaganda boom if any of this personnel are detained by a hostile government or captured by a terrorist group,” said Malcolm Nance, a former U.S. Navy intelligence specialist. “There would be no denying who you are and what you do.” A Pentagon official added: “I don’t recall another time where special-operation forces had to pose with their faces visible while serving in a war zone.”