How good are those Patriot missiles?

Military analysis.
March 24 2003 6:22 PM

Patriot Games

The missile didn't really work in 1991. Is it working now?

Excuse me if I withhold judgment for the moment on the reported successes of the Patriot missile. The new version of the air-defense weapon, known as the Patriot Advanced Capability-3 (or PAC-3) is said to have intercepted four of the six missiles that Iraq has fired at Kuwait.

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This is an impressive record, if true. But I remember that, shortly after Operation Desert Storm, the first war against Iraq in 1991, the U.S. Army claimed that an earlier model of the Patriot had intercepted 45 out of 47 Iraqi Scuds—a 95 percent success rate. Over the following year, the Army lowered its estimate, stating that Patriots intercepted 79 percent of the Scuds launched over Saudi Arabia and 40 percent of those fired at Israel. These remain the official figures today.

However, even the revisions wildly overstate the Patriot's performance in Desert Storm. A later report by the General Accounting Office concluded that Patriot missiles destroyed only 9 percent of the Scuds they tried to engage. The Israeli Defense Force calculated they'd destroyed just 2 percent. William Cohen, Bill Clinton's secretary of defense, admitted upon leaving office in January 2001, "The Patriot didn't work."

Army officers weren't lying when making those earlier claims, but they were manipulating the fine print. A Patriot was counted as having made a successful "intercept" when it got within lethal range of the Scud and its fuse exploded. By this definition, a Patriot could "intercept" a Scud without necessarily destroying it. As early as July 1991, five months after the completion of Desert Storm, a congressionally mandated report by the Defense Department concluded that, while the Patriot "intercepted a high percentage" of Scuds, it sometimes failed to destroy the Scud's warhead and therefore "did not always prevent damage" to soldiers or civilians below.

The early boasts for the Patriot were also caused by misinterpretations. For example, in one reputedly successful intercept over Riyadh, Saudi Arabia, subsequent analysis revealed that the Patriot had broken a Scud into several large pieces, one of which hit an office building, killing one person and injuring scores more. On some occasions, the Patriot might have caused more harm than good. The night of Jan. 25, 1991, in Tel Aviv, three Patriots were fired into the air, fell back to earth, and exploded, two of them in residential areas. The Israeli newspaper Ma'ariv reported at the time that one Israeli was killed, 44 were wounded, and 4,156 apartments were destroyed. The Army claimed at the time that the damage was caused by Scuds, which it said the Patriots missed. But an ABC cameraman had filmed the incidents. An Israeli defense spokesman acknowledged to an ABC reporter that the Patriots had caused the damage.

That incident and a few others like it led Ted Postol, an MIT weapons scientist, to testify before a congressional committee, "It is possible that if we had not attempted to defend against Scuds, the level of resulting damage would be no worse than actually occurred." Postol got into big trouble with the Raytheon Corp. and the Pentagon for making this statement. However, I reported at the time for the Boston Globe that, at a classified briefing shortly after Desert Storm at the Mitre Corp. in Bedford, Mass., three Raytheon engineers were asked by a roomful of weapons scientists whether the Patriot reduced the damage caused by Scuds. The engineers replied that they did not know. (My sources were two scientists at the meeting, neither of them Postol.)

All this said, it may well be that this time the PAC-3 did knock down four Iraqi missiles, as claimed. First, as is now well-known (and contrary to initial reports), the Iraqi missiles were not Scuds. They were other models of Soviet-built missiles that fly more slowly, at lower altitudes, and across a shorter range, than Scuds. Second, the new Patriot works in a very different way than the old Patriots.

With the old Patriot, known as PAC-2, a radar scanned the sky for missiles or airplanes. (By the way, this earlier model was designed to shoot down planes, not missiles. There is no reason to doubt the report that a Patriot accidentally shot down a British fighter jet.) If an object appeared in the sky, it reflected the radar signal, which bounced back. A computer identified the object and tracked its flight path. After this information was processed, a Patriot missile was launched. The Patriot was tipped with a large fragmentary warhead. When it reached a certain distance from the target, the warhead exploded, blowing up the target (or such was the hope) in the process. The PAC-3 utilizes a more precise, longer-range radar and faster data-processing systems. And the missile doesn't carry a warhead; rather, it is designed to slam into the target (this is why it's called an HTK, or "hit-to-kill," weapon). There are two major advantages to HTK, in theory. First, if the Patriot is fired mistakenly or wildly misses, it won't explode when it falls back to earth. Second, there is less room for fudging the definition of "intercept"—the term means that the Patriot actually hit the target. (Whether the target is destroyed, however, remains an issue.)

However, the evidence is mixed on whether the PAC-3 can actually perform this complex task. In "development tests," which are designed to see if the technology works on the most basic level, the new Patriot did very well, hitting 10 out of 11 targets. However, in "operational tests," which are supposed to simulate real combat, the missile did much less well, slamming into the target in fewer than half the engagements, due mainly to computer glitches. (These figures come from a knowledgeable Pentagon official, but see also this.)

Many times during Desert Storm, officials thought that a Scud was shot down by a Patriot, when in fact the Scud had simply broken up into small fragments or gone far astray. That may be what happened to some of the presumably downed missiles in this war, too. (All of them, like the Scuds, are Soviet-made missiles and are known to be neither very stable nor accurate.) Then again, maybe the new, improved Patriot hit them. If so, the hits would signify a dramatic technological advance. For now, though, I'm with the knowledgeable Pentagon official, who told me, "I'm going to wait till the facts are in."

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