The U.S. Army recently revealed that it had sent an air defense battery to Iraq in late 2015. This unit was equipped to protect an Iraqi base used by American troops from ISIL (Islamic State in Iraq and the Levant) artillery, mortar and rocket attack. This battery was equipped with C-RAM (Counter-Rockets And Missiles) systems that had been used in Iraq and Afghanistan since 2006. The unit sent to Iraq had recently served in Afghanistan and defeated several ISIL attacks.
C-RAM is a land-based version of the U.S. Navy Phalanx anti-missile system. Phalanx is the last line of defense against anti-ship missiles. C-RAM was first created to defend American bases in Iraq and Afghanistan. Several foreign nations have since bought C-RAM and users are satisfied with its performance. C-RAM works 24/7 and needs a lot of maintenance. Often civilians (usually retired sailors with Phalanx experience) are hired to operate and maintain C-RAM systems. Phalanx is used by sixteen other navies besides the American fleet.
C-RAM is basically the Phalanx naval gun system with new software that enables it to take data from its own, or other radar systems and shoot down just about any kind of artillery shell or rocket within range. It 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 original Phalanx used 20mm depleted uranium shells to slice through incoming missiles but the high-explosive shell was needed to ensure destruction of the smaller (than missiles) targets shells and rockets presented. Phalanx 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 nearby that a mortar or rocket attack is underway, giving people an opportunity to duck inside if they are out and about.
The first C-RAM was sent to Iraq in late 2006, to protect the Green Zone (the large area in Baghdad turned into an American base). It was found that C-RAM could knock down 70-80 percent of the rockets and mortar shells fired within range of its cannon and that success rate has gone up because of hardware and software tweaks as well as operator experience. Other improvements included the ability to detect low altitude (flat trajectory) rockets and home-made rockets that are not as predictable as factory made stuff.
The first C-RAM systems in Iraq intercepted several hundred rockets or mortar shells aimed at the Green Zone and other bases. Not bad, since C-RAM only took about a year to develop. A C-RAM system, which can cover an area about four kilometers wide, costs $15 million. There is also a mobile version, mounted on a flatbed trailer and hauled by a tractor.