While the cruise missile is universally regarded as almost synonymous to a nuclear missile, and has almost entirelly replaced more traditional means of delivery, like aerial bomb, not every cruise missile carries a nuclear warhead (though most are capable of doing so). The origins of cruise missile can be traced back to World War I and Lawrence Sperry's "Flying Torpedo", a small unmanned airplane equipped with simple autopilot and explosive charge. In the World War II, English pilots were forced to fight with Luftwaffe V-1's, jet-powered "flying torpedoes" that were used to bombard London; perhaps it was the first time, when men fought machines (though the machines were unable to fight back yet). V-1 was wildly inaccurate and quite easy to intercept, yet the developement of such weapons gained momentum with impeding Cold War. In 1956, US Air Force deployed first MGM-1 Matadors, nuclear-capable missiles based on V-1 design, but with added radio link for in-flight course corrections. Later designs of cruise missiles featured much more advanced means of guidance, like satellite guidance and TERCOM (terrain contour matching) system, made possible by advances in computing power and allowing for pinpoint accuracy without any outside help. They could also be launched not only from the ground, but also from a plane, a ship or a submarine. By the year 2000, all nuclear-armed countries had some kind of nuclear-capable cruise missile in their arsenals.