Surveillance video from the Washington Navy Yard released by the FBI shows that murderer Aaron Alexis had minimal skill with his firearm, suggesting that if military officers were allowed to carry firearms on base, the outcome might have been much different.

The 30-seconds of video security footage include Alexis’s Toyota Prius entering a Navy Yard parking facility before it shows him following another employee through the door into Building 197 with the computer bag holding his disassembled shotgun and ammunition slung over his shoulder.

The FBI video then cuts to footage of Alexis hesitating in an empty corridor with his cut-down shotgun before he descends a flight of stairs and enters another office hallway through glass doors, using his trigger hand to open the door before darting furtively across the hallway. Alexis then peaks his head around the corner to assess the situation, then trots to a row of cubicles before the video ends.

The limited footage shown strongly suggests that Aaron Alexis had minimal competence with his firearm, and little to no training beyond what he picked up from the movies and video games.

His military experience in the Navy was limited to serving as an aviation electrician’s mate, a non-combatant position.

If military officers in the building carried firearms—or if Marines on site trained for close-quarters battle were allowed ammunition—they would have been able to control choke-points within the building.

Marines with M4 carbines or shotguns could have easily stopped Alexis as he hesitated in the empty corridor, or at the moment when he entered the “fatal funnel” of the glass stairwell doorway, where Alexis let down his guard and took his trigger hand away from his shotgun rendering him and easy target to anyone guarding the access point.

Many have blamed a Clinton-era order for Fort Hood and the Navy Yard becoming “gun free zones,” but the directive was originally established under George H.W. Bush in 1992, before being reissued in 2011.

Both parties bear some blame for the policy; the question is whether the Obama Administration will reverse the policy after 28 have been murdered and 40 injured in on-base mass shootings on his watch.