no attacks in Canada, Mexico, South America, or Asia.
Europes proximity to the Mideast is what makes them challenging. The refugees literally just walked there in the millions. It's trivial to sneak someone in. For the US you have to get on an official US plane or boat.
And as comagnun has said, he US already had the secret sauce.
Isis and al queda love trumps policy btw. This is their goal. Incite more hatred between the west and ordinary muslims. It gives them a stronger base and this more power.
Kinda like how trump found disaffected hard working honest people in the Midwest and convinced them that a formerly democrat New York billionaire who lives in a solid gold house understands their plight.