The U.S. Air Force is running into intractable problems with it's Airborne Laser program. The system, mounted in a modified B-747 aircraft, operates at 40,000 feet and fires a laser that can knock down an ICBMs as they lift off into space. There have been successful tests, and another test is being prepared now. But the system uses four tons of chemicals for each shot, and system reliability is not what it should be. While the program has $600 million to work with this year, the Department of Defense is considering cutting that back and waiting for the technology to become more compact and reliable. Israeli researchers have developed a more efficient laser technology. It is thought that the current laser technology will never be made combat ready, at least not at a cost (in time and money) that is affordable. Thus new approaches, such as the Israeli one, appear a better way to go. But this would mean replacing most of the equipment on the Airborne Laser aircraft and going through the test program all over again. More time consuming, but likely to produce a cheaper and more effective weapon in the future.