Predators and Reapers are designed for what's termed a "permissive" environment—basically anywhere that doesn't have the capability to shoot them down, or for political reasons chooses not to. The United States actually fights most of its wars in places like Afghanistan (and formerly Iraq), where America and her allies command the skies, or countries like Yemen, Somalia, and Pakistan, where the official government doesn't mind the U.S. attacking hostile local insurgents. Insurgents, it turns out, don't usually have the kind of weapons that are good for shooting aircraft out of the sky. Sometimes, an insurgent group like al Qaeda in the Arabian Peninsula can get small, portable, anti-air missiles, but those can be intercepted in transit. Afghanistan's Taliban scored their biggest success against aircraft when they blew up eight Harrier fighters on the ground at a base they infiltrated. Those are risky attacks, and while they can stop the occasional a drone, they can't really clear the sky of them.