Crude intercontinental ballistic missiles from "rogue" states such as Iraq or North Korea are precisely those least likely to be shot down by the missile defence system being planned by the US, a report in yesterday's New York Times has warned.
Pentagon sources confirmed the problem. "We've concluded that it's an extremely difficult problem," a Pentagon anti-missile scientist told the newspaper.
The report, which casts further serious doubt on the central rationale of the US's controversial missile defence programme, quotes missile experts warning that the irregular tumbling motion of more technically primitive missiles makes them harder to pinpoint and virtually indistinguishable from decoys deployed to confuse defensive interceptor systems.
The revelation is certain to add to domestic criticism of President George Bush, who confirmed on Friday his determination to press ahead with missile defence and repudiate the Anti-Ballistic Missile (ABM) treaty.
Mr Bush has argued the new system is needed to counter the threat from "rogue" states such as Iraq and North Korea whose irrational leaders are developing a missile capacity and may no longer be deterred from a last-ditch attack on the US by the traditional concept of mutually assured destruction, the cornerstone of the ABM philosophy.
Sophisticated interballistic missiles are targeted by being given a spin akin to a top or rifle bullet but such a technique is difficult to achieve. Those just developing the technology are likely to rely on missiles which may tumble wildly as they fly, in some cases end on end. Their lack of accuracy is unlikely to be of concern - if unable to target Central Park, hitting Manhattan is likely to be feasible. For some experts the tumbling problem adds degrees of complexity that may call into question the viability of a missile defence system altogether.
"Tumbling is a terribly big deal," said Dr Theodore A. Postol, an arms expert at the Massachusetts Institute of Technology critical of some antimissile systems. "It's totally unpredictable, a wild card. It makes it much harder to know what to look for."
To date, the US has demonstrated the ability to hit incoming missiles in only one out of three tests, in each case with missiles using spin stabilisation. Tests, which cost $100 million a time, using cruder missiles are scheduled, but not for a couple of years.
"It is a walk-before-you-run, learn-as-you-go development approach," Lieut Gen Ronald T. Kadish, the antimissile programme's director, told the House Armed Services subcommittee.
