His biggest problem is the US stepping onto 'holy' arab soil

I believe you have this backwards. His biggest problem is he is a militant Islamic extremist who wants to kill innocent people. From that, all else flows. It's called terrorism and the idea behind terrorism is to terrorize people (by killing ordinary innocent people) into doing your will even though you have no authority. He is not the government of any country much less of a country in which the US has a presence with that country's agreement.