Two Phalanx anti missile system have been sent to Iraq, modified to destroy rockets and mortar shells fired into the Green Zone (the large area in Baghdad turned into an American base). The Phalanx is a 20mm cannon designed to defend American warships, by destroying anti-ship missiles. Phalanx does this by using a radar that immediately starts firing at any incoming missile it detects. The modified versions sent to Iraq, called the C-RAM (Counter-Rocket Artillery Mortar) system has had its software modified to detect smaller objects (like 82mm mortar shells). The original Phalanx, it was found, could take out incoming 155mm artillery shells. This capability is what led to C-RAM. The other modifications include linking Phalanx to the Lightweight Counter Mortar Radar and Q-36 Target Acquisition Radar. When these radars detect incoming fire, C-RAM points toward the incoming objects and prepares to fire at anything that comes within range of its cannon. C-RAM also uses high explosive 20mm shells, that detonate near the target, spraying it with fragments. By the time these fragments reach the ground, they are generally too small to injure anyone. The Vulcan used 20mm depleted uranium shells, to slice through incoming missiles. The C-RAM, like the Vulcan, fires shells at the rate of 75 per second. Another advantage of C-RAM, is that it makes a distinctive noise when firing, warning people in the Green Zone that a mortar or rocket attack is underway, giving people an opportunity to duck inside if they are out and about. Without C-RAM to stop the incoming shells, they usually land without hitting people. The Green Zone is a big place, but something usually gets damaged during each attack, and sometimes the shells are duds, meaning they remain dangerous until found and removed. It took about a year, from the time an army general demanded that some kind of anti-mortar weapon be found, until the first C-RAMs arrived in Iraq.