September18, 2008:  The latest version of the U.S. anti-radiation missile, the AGM-88D, uses GPS so that the missile, which normally homes in on radar transmissions, can be used to attack targets by location alone. The AGM-88 moves at high speed (2,200 kilometers an hour, or 36 kilometers a minute) to hit targets 100 kilometers away. This version of the AGM-88 costs less than $100,000 each. The standard version uses more complex sensors which can detect and guide the missile to a wide variety of radar signals. These versions cost about $300,000 each. GPS enables HARM (or the aircraft carrying it) to locate a radar when it is turned on, store the GPS location, then go after the target regardless of whether it is turned on or off.

Another recent model of the traditional version, the AGM-88E, uses a more expensive approach to nailing enemy radars that are turned on briefly, and attempts to avoid destruction by quickly turning off power. The missile, also called the Advanced Anti-Radiation Guided Missile (AARGM), was developed jointly by U.S. and Italian firms. The original AGM-88 has been in use since the 1980s, and the original 1960s anti- radiation missile quickly evolved into what was called HARM (High Speed Anti-Radiation Missile).

The AGM-88E version defeats the favorite trick of anti-aircraft units, shutting down their radars when they note a HARM is on the way. The AGM-88E remembers where the radar is when it was on, and carries its own high resolution (millimeter wave) radar to make sure it gets the radar. Finally, the AGM-88E can transmit a picture of the target, just before it is hit, so the user can be certain of what was taken out. Currently, there are orders for over 2,000 of these missiles from the U.S. Navy and Marine Corps, Italy and Germany. Production began last year, on what appears to be an endless line of HARM variants.