The U.S. Army has ordered another 44 HIMARS rocket launchers, for $3.2 million each. These will be delivered over the next two years, and give the army a total of 375 HIMARs vehicles. It was because of the success of the GPS version of the U.S. MLRS rocket, that the smaller, truck mounted MLRS (HIMARS) rocket launcher system became the most popular vehicle for launching the rocket. HIMARS carries only one, six MLRS rocket, container (instead of two in the original MLRS vehicle), but the 12 ton truck can fit into a C-130 transport (unlike the 22 ton tracked MLRS) and is much cheaper to operate. The first HIMARS entered service in 2005, about a year after GPS guided rockets did.
The 309 kg (680 pound) GMLRS (guided multiple launch rocket system) missile is a GPS guided 227mm rocket that entered service seven years ago. It was designed to have a range of 70 kilometers and the ability to land within meters of its intended target, at any range. This is possible because it uses GPS (plus a back up, less accurate, inertial guidance system) to find its target. Two years ago, the army tested GMLRS at max range (about 85 kilometers) and found that it worked fine. This enables one HIMARS vehicle to provide support over a frontage of 170 kilometers, or, in places like Afghanistan, where the fighting can be anywhere, an area of over 20,000 square kilometers. This is a huge footprint for a single weapon (an individual HIMARS vehicle), and fundamentally changed the way you deploy artillery in combat. Russia and China have followed suit and converted many of their unguided rockets systems to ones that use GPS guided versions.
The U.S. Army is getting most of the 900 HIMARS vehicles planned, with the marines getting the rest. There are also several export customers. The U.S. Army is buying 100,000 GMLRS rockets, most of them fitted with a 89 kg (196 pound) high explosive warhead. These have been used with great success in Iraq and Afghanistan, where over a thousand have been fired so far. The guided rocket is much more effective than the older, unguided, version, and is replacing it in most cases. No more of the unguided rockets are being purchased by the U.S. The accuracy of GMLRS means that one or two rockets does the job that previously required a dozen or more of the unguided ones. That's why HIMARS is so popular. While it only carries six rockets, that's often enough to last for days, even when there's a lot of combat. HIMARS can be reloaded, with another container of six GPS guided rockets, in less than ten minutes.