ISIS doesn't have to travel. It can radicalize those in place to do their evil work. It can take credit even if it had no prior direct knowledge of the perp if they claim allegience as they attack. Israeli intel protects her some, but her strong guard protects her more. Even so, locals can strike without warning. In Israel, there is a duty to report. We could have the same if we remove bancruptcy protection from those whose silence proved complicit in an attack.