The U.S. Patriot air defense missile system had a very mixed record in Iraq, and some aspects of it's performance are still not well known. Patriots shot down two aircraft, one British Tornado on March 23rd, and an American F-18C was shot down a week later. But there was a third incident, on March 24th, where an American F-16, looking for any Iraqi air defense systems, noted that it was being tracked by a ground radar. The F-16 promptly launched an radar homing ("anti-radiation") HARM missile that damaged the Patriot radar responsible.  Fortunately, the crew of the Patriot battery had taken cover because of Iraqi mortar fire, and left their radar and launcher on automatic. Despite the missile attack, the Patriot software apparently picked up the F-16s IFF signal and recognized the aircraft as friendly, if a bit trigger happy. Some Patriot batteries were brought forward to protect troops against Iraqi missiles. There is still no clear evidence that the Patriot shot down any Iraqi missiles. It appears that all the Iraqi missiles were either fired blindly, or their guidance systems didnt work very well. Iraq appears to have fired up to 20 Ababil-100 and al-Samoud-2 missiles. These are short range missiles, not capable of going more than 150 kilometers. The U.S. says that nine of them were "engaged" by Patriot, but it's unknown if evidence (Iraqi and American missile debris) are still being collected to see if the Iraqi missiles were hit. It is known that two low flying Iraqi cruise missiles (Chinese CSSC-3s) were launched at Kuwait on March 29th and 30th. The missiles landed in Kuwait, but no Patriot radar picked them up. The Patriot has definitely shot down missiles in tests, and now has shot down two jet fighters in a combat zone. But it was noted that the combat zone contained something that the test ranges did not, lots and lots of electronic signals (radars, radios, electronic counter measures.) Patriot operators have noticed that this cacophony of electronic signals does have an effect on Patriot radars and guidance systems. Exactly what effect is not known yet.