More likely, ISIS is doing a common tactic amongst guerilla fighters and terrorist organizations: Setting up a global network with checkpoints and outposts to smuggle people, goods, and other such commerce generating activities. After all, not even terrorism is free: something has gotta buy those ak-47's. Like drugs shipped with cartels up into the states. It's also an effective way to recruit more educated, world knowledgeable people. Canada has had this kind of issue before as well, with certain Islamic minorities feeling isolated and the more extreme among them siding with terrorist organizations that they believe represent their interests, often being indoctrinated into them with images of paradises nobody has seen.

I would not panic about any kind of real assault, though now that we know, we might be able to curb potential market growth for their products.