December17, 2006: The U.S. Navy successfully tested the new Tomahawk Block 4 cruise missile, which was launched from a destroyer. The major new feature of the Block 4 missile is a two way datalink, and the ability to send the missile to another target, after it is launched, or even have it fly in circles, or use its onboard camera to look for a target. Tomahawk now uses GPS. The missile has a maximum range of 1,500 kilometers, and can stay in the air for about two hours. Over a thousand Block 4 missiles will be created by upgrading existing anti-ship versions.