Compared to many aeronautical curiosities that have taken wing at NASA's Dryden Flight Research Center at California's Edwards Air Force Base over the years, the latest military test stunts did not appear very remarkable. Last April, a low-slung aircraft, about the size of a sport utility vehicle but with batlike wings similar to those of the B-2 stealth bomber, took off, flew at 10,500 meters and then dropped a 110-kilogram inert precision bomb while zipping along at 700 kilometers per hour. Four months later, a pair of the aircraft took off and flew together. These were modest stunts, to be sure, except for this fact: the jets have no pilots. They are the future of warfare, the first working models of networked autonomous attack jets, and the U.S. Department of Defense would like to start building them by 2010.

Eventually such planes will be military mainstays. Of this, most observers are sure; it is simply a lot less expensive -- and safer -- to send machines into battle than to send people, who require food, sleep, training, and pay. Humans can only tolerate so much G-force and are prone to error; unmanned aircraft have the potential to be more dependable. Already, lone unmanned planes -- with humans at the remote controls -- are widely used for surveillance. But the next crop of planes will fly in coordinated groups, with more autonomy. They'll tackle jobs such as attacking enemy air defenses, identifying new targets, and releasing precision bombs. "The long-range vision is that the president will wake up some day and decide he doesn't like the cut of someone's jib and send thither infinite numbers of myrmidons -- robotic warriors -- and that we could wage a war in which we wouldn't put at risk our precious skins" is how John Pike, director of GlobalSecurity.org, a leading defense policy website, puts it.