Tomahawk Cruise missiles may be known for their pinpoint accuracy, but when it comes to speed, there's no topping the X-51. As part of the Pentagon's Prompt Global Strike project, the X-51 is a hypersonic cruise missile that can strike anywhere in the world in less than an hour. The new missile, which is designed to hit Mach 5 (3,600 mph), destroys its targets by crashing into them at top speed. Tomahawks by comparison, top out at 550 mph. The Pentagon is hoping to test run the X-51 by 2008, despite protests that these missiles could trigger a nuclear war. I gotta say, World War III aside, these missiles are mighty impressive considering how difficult it is to maintain hypersonic flight.
Hypersonic Cruise Missile [Popular Mechanics]