While the United States Air Forces A-10 ground attack aircraft received high marks for its performance in Iraq, it's also being used for homeland defense. It was noted last year that terrorists might buy or rent one or two engine propeller driven aircraft for suicide attacks. These aircraft are so slow that the usual air defense aircraft, like the F-16, would not be able to slow down enough to check out suspicious aircraft. The A-10, however, is slow enough,  and many are kept fueled and armed at all times for interception of suspicious, slow moving, and low flying aircraft.