The U.S. Air Force has successfully tested its new Paveway II Plus laser guided bomb. The existing Paveway II bomb has a range of 14 kilometers and will hit within less than half a meter of where the laser designator is reflecting off the target. Paveway is actually a guidance kit (costing about $20,000) that is fitted to a dumb bomb, turning it into a glide bomb that homes in on the reflected laser light. The Paveway II Plus is more accurate and reliable, but the exact figures are classified.
Laser guided bombs have been in use since the 1960s. In the 1990s they were replaced, for a lot of missions, by GPS (satellite) guidance, which will land the bomb within 10 meters (31 feet) of the location specified. The backup inertial system will only get the bomb to within 50 meters. This was a major improvement over the older laser guided bombs. These weapons could get the bomb to within three meters of the target, but were subject to getting lost if there was a lot of rain, fog or blowing sand around the target. In those cases, the bomb would miss by a hundred or more meters. Moreover, the GPS has technology to defeat jamming. The anti-jamming features have not gotten a battlefield workout, and are not guaranteed to work in all circumstances. But, overall, the JDAM is the most effective bomb ever built. But if you need greater accuracy (for taking down a bridge, hitting a moving vehicle or destroying an underground bunker), you often need laser guidance.