Recently there was a terrorist attack on a concert hall in Moscow and about 150 people were killed. The actual attackers were rather simple-minded Tajik people. No way they could plan such an attack themselves. You do realize that there was someone else? "A quiet American"? (Or maybe a British; doesn't matter.) Some timidly looking guy visited that concert hall before that attack, walked around and made notes. He noted, for example, whether the finishing materials were flammable. He did that reconnaissance in several places and finally picked that concert hall. That fellow belongs to a group that does this kind of things. They have something like a list of cases, teaching materials and lectures. You don't see such people in the news; but they surely do exist.
This is how a modern Western invasion looks like.