When information first came out about the San Bernardino killer, it was mentioned that he had travelled to Saudi Arabia. But it was dismissed as no big deal, because he was merely going to the Hajj.
That’s a huge deal. Muslims are supposed to do this at least once...before they die. Of course he went to the Hajj before the onset of sudden jihad syndrome.
Hajj stampede killed three times Saudi Arabia’s official number, says report
I call that a good start.