Insider Threat: His country trained him to fight. Then he turned against it. More like him are doing the same:

PART 1: The Rise of Extremism among Military and Veterans

MINI-DOCUMENTARY: Insider Threat - AP investigation finds growing extremism in the US military

PART 2: A Pentagon-funded study on extremism in the military relied on old data, misleading analyses and ignored evidence that pointed to the opposite conclusion.

Following the story:

New Orleans attack and Vegas explosion highlight extremist violence by active military and veterans

Trump Pentagon pick had been flagged by fellow service member as possible ‘Insider Threat’