Video Link: excellent background film on the ABL system
Video Link: film scenario of ABL in action
The Airborne Laser is a unique missile defense system. Essentially a very high-powered chemical laser built into a Boeing 747 airplane, it is intended to detect, target, and destroy ballistic missiles during their boost phase shortly after launch. This would provide a unique capability, allowing shoot-downs of attacking missiles while still flying over their home country.
According to press reports, the ABL will be able to initiate its speed-of-light attack at a range of hundreds of kilometers. Several successful preliminary tests have already taken place; the first missile intercept test of the ABL is expected in late 2009.