I read that in Gulf War Junior, the Patriot missile batteries made exactly zero successful interceptions. Several sources reported that Saddam's Scuds failed/missed all on their own.

On April 7, 1992 Theodore Postol of the Massachusetts Institute of Technology, and Reuven Pedatzur of Tel Aviv University testified before a House Committee stating that, according to their independent analysis of video tapes, the Patriot system had a success rate of below 10%, and perhaps even a zero success rate.[17][18] Also on April 7, 1992 Charles A. Zraket of the Kennedy School of Government, Harvard University and Peter D. Zimmerman of the Center for Strategic and International Studies testified about the calculation of success rates and accuracy in Israel and Saudi Arabia and discounted many of the statements and methodologies in Postol's report.[19][20]

According to Zimmerman, it is important to note the difference in terms when analyzing the performance of the system during the war:

Success Rate – the percentage of Scuds destroyed or deflected to non-populated areas
Accuracy – the percentage of hits out of all the Patriots fired
In accordance with the standard firing doctrine on average four Patriots were launched at each incoming Scud – in Saudi Arabia an average of three Patriots were fired. If every Scud were deflected or destroyed the success rate would be 100% but the Accuracy would only be 25% and 33% respectively.

The Iraqi redesign of the Scuds also played a role. Iraq had redesigned its Soviet-style Scuds to be faster and longer ranged, but the changes weakened the missile and it was more likely to break up upon re-entering the atmosphere. This presented a larger number of targets as it was unclear which piece contained the warhead.

What all these factors mean, according to Zimmerman, is that the calculation of "Kills" becomes more difficult. Is a kill the hitting of a warhead or the hitting of a missile? If the warhead falls into the desert because a PATRIOT hit its Scud, is it a success? What if it hits a populated suburb? What if all four of the engaging PATRIOT missiles hit, but the warhead falls anyway because the Scud broke up?

According to the Zraket testimony there was a lack of high quality photographic equipment necessary to record the interceptions of targets. Therefore, PATRIOT crews recorded each launch on videotape, and damage assessment teams recorded the Scud debris that was found on the ground. Crater analysis was then used to determine if the warhead was destroyed before the debris crashed or not. Furthermore, part of the reason for the 30% improvement in success rate in Saudi Arabia compared to Israel is that the PATRIOT merely had to push the incoming Scud missiles away from military targets in the desert or disable the Scud's warhead in order to avoid casualties, while in Israel the Scuds were aimed directly at cities and civilian populations. The Saudi Government also censored any reporting of Scud damage by the Saudi press. The Israeli Government did not institute the same type of censorship. Furthermore, PATRIOT's success rate in Israel was examined by the IDF (Israel Defense Forces) who did not have a political reason to play up PATRIOT's success rate. The IDF counted any Scud that exploded on the ground (regardless of whether or not it was diverted) as a failure for the Patriot. Meanwhile, the U.S. Army who had many reasons to support a high success rate for PATRIOT, examined the performance of PATRIOT in Saudi Arabia.

Both testimonies state that part of the problems stem from its original design as an anti-aircraft system. PATRIOT was designed with proximity fused warheads, which are designed to explode immediately prior to hitting a target spraying shrapnel out in a fan in front of the missile, either destroying or disabling the target. These missiles were fired at the target's center of mass. With aircraft this was fine, but considering the much higher speeds of TBMs, as well as the location of the warhead (usually in the nose), PATRIOT would most often hit closer to the tail of the Scud due to the delay present in the proximity fused warhead, thus not destroying the TBM's warhead and allowing it to fall to earth.

In response to the testimonies and other evidence, the staff of the House Government Operations Subcommittee on Legislation and National Security reported, "The Patriot missile system was not the spectacular success in the Persian Gulf War that the American public was led to believe. There is little evidence to prove that the Patriot hit more than a few Scud missiles launched by Iraq during the Gulf War, and there are some doubts about even these engagements. The public and the United States Congress were misled by definitive statements of success issued by administration and Raytheon representatives during and after the war."[21]

A Fifth Estate documentary, quotes the former Israeli Defense Minister as saying the Israeli government was so dissatisfied with the performance of the missile defense, that they were preparing their own military retaliation on Iraq regardless of US objections.[22] That response was cancelled only with the cease fire with Iraq.