Review Cites Flaws In U.S. Missile Defense Program


Published: May 17, 2010

President Obama’s plans for reducing America’s nuclear arsenal and defeating Iran’s missiles rely heavily on a new generation of antimissile defenses, which last year he called “proven and effective.”

His confidence in the heart of the system, a rocket-powered interceptor known as the SM-3, was particularly notable because as a senator and presidential candidate he had previously criticized antimissile arms. But now, a new analysis being published by two antimissile critics, at M.I.T. and Cornell, casts doubt on the reliability of the new weapon.

Mr. Obama’s announcement of his new antimissile plan in September was based on the Pentagon’s assessment that the SM-3, or Standard Missile 3, had intercepted 84 percent of incoming targets in tests. But a re-examination of results from 10 of those apparently successful tests by Theodore A. Postol and George N. Lewis, being published this month, finds only one or two successful intercepts — for a success rate of 10 to 20 percent.

Most of the approaching warheads, they say, would have been knocked off course but not destroyed. While that might work against a conventionally armed missile, it suggests that a nuclear warhead might still detonate. At issue is whether the SM-3 needs to strike and destroy the warhead of a missile — as the Pentagon says on its Web site.

“The system is highly fragile and brittle and will intercept warheads only by accident, if ever,” said Dr. Postol, a former Pentagon science adviser who forcefully criticized the performance of the Patriot antimissile system in the 1991 Persian Gulf war.

In interviews and a statement, the Pentagon’s Missile Defense Agency strongly defended the SM-3s testing record, and said that the analysis by Dr. Postol, an M.I.T. physicist, and Dr. Lewis, a Cornell physicist, was fundamentally mistaken.

“The allegation is wrong,” Richard Lehner, an agency spokesman, said Wednesday. He said the SM-3 is “attaining test scores that many other Defense Department programs aspire to attain.”

Even so, the Pentagon later admitted that 4 of the 10 analyzed flight tests carried no mock warheads at all.

The White House declined to comment on the critique of the SM-3 and referred questions to the Pentagon.

The political implications of the critique are potentially large. Democrats, traditional critics of missile defense, have been largely silent about Mr. Obama’s enthusiasm for this new generation, which for the moment is aimed only at shorter- and mid-range missiles, rather than ones that fly between continents.

During the campaign, Mr. Obama repeatedly criticized what he called President George W. Bush’s haste to deploy unproven antimissile arms. He vowed that as president, he would assure that any defensive shield would meet rigorous standards of testing and effectiveness.

Since last fall, Mr. Obama’s antimissile goals have expanded to include not only countering Iranian missiles, but creating a rationale for deep cuts in the nation’s nuclear arsenal and ultimately for prompting foes to abandon their missile programs.

The deployment of the SM-3 is also seen as essential to convincing Israel that the United States has an effective technology to contain Iran, even if the Iranians obtain a nuclear weapon.

The dispute between the academics and the Pentagon centers on whether it is enough for a speeding interceptor to hit the body of a spent rocket moving through outer space or whether it must hit the attached warhead. Dr. Postol says the SM-3 interceptor must shatter the warhead directly, and public statements of the Pentagon agency seem to suggest that it agrees.

“The interceptors,” the agency Web site says in its basic explanation of antimissile goals, “ram the warhead at a very high closing speed, destroying the target.”

Skeptics generally hold that the antimissile job is so daunting — what the Pentagon calls hitting a bullet with a bullet — that managers and contractors easily fall prey to exaggerating test results.

But technologists call it increasingly doable. Compared with the Bush administration’s land-based system, the SM-3 is fairly small, quickly deployable on ships and has a better reputation.

The interceptor holds what the Pentagon calls an exoatmospheric kill vehicle. In space, it peers through a telescope to guide itself toward the target, sensing telltale heat emanations and using a computer brain to fire thruster jets. The kill vehicle slams into the target and destroys it by force of impact.

Dr. Postol’s critics see him as a pessimist blind to antimissile progress, and his defenders view him as a seer of technical oversight.


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