President Donald Trump may have inadvertently unmasked a Navy SEAL team during his short visit to a US base in Iraq this week.

Ordinarily, the whereabouts of special operations forces are a closely held secret. In the rare instances when they are filmed while in a combat zone, their faces and other identifying features are usually blurred out.

But after his lightning trip to Al-Asad Air Base in western Iraq on Wednesday, Trump tweeted a video of him posing for photos with US troops, shaking their hands and signing mementos.

In one scene, he is giving a thumbs up alongside a group of what appears to be special operations forces.According to the pool report of the event, held in a dining hall at the base, a man called Kyu Lee told Trump he was the chaplain for SEAL Team Five.

While the president has broad authority to declassify information, so his tweet likely didn’t run afoul of any rules, some observers called it a breach of operational security.

Revealing identities “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,” Malcolm Nance, a former US Navy intelligence specialist told Newsweek.Special Operations Command did not immediately respond to a request for comment.