The U.S. Air Force has decided to cancel upgrades to the B-1 bomber defensive systems. The B-1s electronics have long had development and operational problems. Moreover, it costs twice as much to deliver a bomb via a B-1 than with a much older (and cheaper) B-52. Many in the Pentagon would prefer to retire the B-1, which is more expensive to operate than the B-52 and not nearly as capable as the more recent B-2. The success of guided bombs had made it possible to successfully attack the same number of targets with far fewer bombers. The accuracy of JDAM and other smart bombs has reached the point where smaller (250 and 500 pound) smart bombs are on the way, which will allow one bomber, or fighter-bomber, to destroy even more targets. This makes the 91 B-1s difficult to justify.