The Iraq war shows once more the enormous impact of GPS on military operations. The military has always had a lot of problems with "land navigation." The old joke about "the most dangerous thing in the world is a 2nd Lieutenant and a map" is really no joke. During the 1991 Gulf War, hundreds of troops (or their parents) ponied up $4000 for commercial GPS receivers. The 1991 Gulf War "left hook" would not have been possible without GPS (which was not fully functional then for several hours every afternoon there was no signal because all the satellites were not up yet.) The military was enthusiastic about GPS from the start (it was, after all, a Department of Defense program) and JDAM (GPS guided bombs) quickly followed, as did command and communications systems based on GPS. Because GPS receivers get cheaper every year (commercial receivers can be had for under $100 and all cell phones will have them after 2006), the military will be building them into more vehicles, weapons and other equipment. This has made it possible for warplanes to find ground units in need of bombing support. New technology, developed by civilian firms, provides improved "adjustment signals" for what the GPS satellites are transmitting, providing accuracy measured in inches, not feet or yards. But most of the benefit was in the area of troop navigation, and weapons accuracy.