President 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.