Until the Iraq campaign, the U.S. Army had planned to have a mix of it's ATACMS missiles, half being the 180 kilometers version, half the 300 kilometers one. The ATACMS is a fired from the MLRS launcher, where one ATACMS missile (in a firing container) replaces the standard (and same size) MLRS container carrying six smaller rockets. But in Iraq, 75 percent of the ATACMS targets were farther than 180 kilometers away. The ATACMS uses GPS as part of its guidance system and is thus available for use around the clock and in all kinds of weather. Thus it became a very popular weapon for hitting distant targets that might move shortly. Each ATACMS costs about $100,000, making it more than three times as expensive a weapon than a smart bomb dropped from an aircraft. But when the air force is not available, the army wants to have some long range firepower available. The longer range ATACMS has a smaller warhead, carrying about a third of the lethal load. But because of the ATACMS accuracy, that is sufficient for most targets. The ATACMS warhead can carry either 300 bomblets (in the 300 kilometers version, 950 bomblets in the shorter range rocket), high explosives or robotic anti-tank weapons (BATs). The army is also using a navy bunker buster warhead, and is buying at least 180 new ATACMS missiles. All will apparently be the longer range version. The mix of warheads is not yet decided.