U.S. Missile Defense Offers No Safety, Scientists Say

By David Ruppe
Global Security Newswire

WASHINGTON — The 20-interceptor long-range missile defense system President George W. Bush has ordered fielded over the next two years will provide the United States almost no protection against an attack, a new analysis by nongovernmental scientists argues.

Furthermore, the additional 20 missiles the administration plans to field in 2006 and 2007 are unlikely to significantly improve the probability of success, the study calculates.

The analysis released yesterday, titled Technical Realities: An Analysis of the 2004 Deployment of the a U.S. National Missile Defense System, was written by Union of Concerned Scientists physicists Lisbeth Gronlund and David Wright, MIT professor George Lewis, and Center for Defense Information senior adviser Philip Coyle.

Noting that the Ground-based Midcourse Defense (GMD) has not yet been tested or proven to work under operationally realistic conditions, the authors judged the system’s potential effectiveness by assessing its acknowledged technical limitations and complexity, and the inherent uncertainty about the nature of any attack.

Those factors, the report argues, dramatically reduce the system’s “kill probability” — the potential that a single interceptor could destroy an attacking warhead. Mathematically, the report argues further, a low kill probability could not be offset by firing the number of interceptors planned by the administration. For example, it calculates that if each interceptor had a kill probability of 10 percent, then 20 interceptors would have only a half-percent likelihood of successfully stopping five attacking warheads.

“Our technical analysis of this proposed system shows there is no basis to believe that it will have any defensive capability,” said Gronlund.

“Deploying more interceptors will not address the fundamental limitations of the Block 2004 [fiscal 2004 and 2005] system that severely constrain its effectiveness, nor will they improve its defensive capability in a meaningful way,” the report says further.

Missile Defense Agency officials have argued that the system has demonstrated some limited defensive capability against any likely near-term threat, that some capability is better than none, and that increasing the number of interceptors could significantly increase the system’s effectiveness.

“We have established a basic level of confidence with the technology and are ready to mount a limited defense where we presently have none,” agency spokesman Richard Lehner said today in response to the report. 

The report recommends canceling the administration’s fielding plans. The Missile Defense Agency is seeking funding this year to begin work on fielding the second batch of up to 20 interceptors, and this month key committees in the House and Senate approved the request.

The scientists based their conclusions on an analysis of the technical capabilities of the system expected to be in place by the end of 2005. They argue that decoys and other countermeasures could easily fool an interceptor, significantly decreasing the probability of success.

“Unsophisticated countermeasures that could readily be implemented by countries such as North Korea remain an unsolved problem,” the analysis says.

It cites a recent Missile Defense Agency statement concurring with that conclusion, made in a February 2004 General Accounting Office report. The GAO report said a “notable limitation of system effectiveness is the inability of system radars to perform rigorous target discrimination.”

MDA responded to the report, “The GAO report correctly identifies the challenges any of our midcourse defensive systems and sensor systems would face in the presence of various decoys and countermeasures” (see GSN, March 11).

The scientists’ analysis also concludes that the ground-based system will lack sensor capabilities necessary for tracking a North Korean missile headed for Hawaii.

“The Block 2004 system will be able to provide only limited tracking information about a missile attack by North Korea on Hawaii, resulting in a large uncertainly in the location of the threat cloud,” it says.

Senior U.S. officials have suggested the planned system could have significant capability against a North Korean attack.

Missile Defense Agency Director Lt. Gen. Ronald Kadish said at a hearing in April that the system would have “very high odds,” and a “substantially greater than zero” chance of engaging and destroying likely threats. He refused to quantify the estimated probability in public.

Last year, then-Undersecretary of Defense for Acquisition, Technology and Logistics Edward Aldridge though told Congress the system would have a 90-percent probability of defeating a simple single warhead attack using multiple interceptors (see GSN, March 21, 2003).

The Missile Defense Agency this year invited reporters to participate in a computerized war game simulating a defense using the system that the scientists said assumed a 91-percent kill probability (see GSN, March 17).

The analysis argues such assumptions are unrealistic.

“Based on the poor defense capability in the face of unsophisticated countermeasures, the kill probability is likely to be low, not high,” it says.

The inherent complexity of the system will also inevitably further reduce the chances for success, the report says, citing a need for successful tracking, communications, missile launch, separation of the kill vehicle, detection of the target cluster, discrimination of the warhead, and homing by the kill vehicle.

“The kill probability will depend on the successful completion of several tasks (none of which have been demonstrated for the GMD system under realistic flight conditions),” it says, and concludes the kill probability of the initial system “is likely to be very low.”

Kadish has asserted that the system’s record of intercepting five of eight targets in flight tests demonstrates a basic capability. The report argues the intercept tests were highly controlled, to the point that key weaknesses, such as discrimination, were not tested realistically. 

“The system remains in an early stage of development, and … the testing program has provided essentially no data about how the system would perform in a real missile attack,” it says.

“Demonstrating hit-to-kill does not prove the concept of midcourse defense,” it says.

Arguing for funds to field a second batch of 20 interceptors, MDA Director Kadish argued at a congressional hearing in March that the number of interceptors, not any hardware limitations, is the primary factor affecting the system’s potential effectiveness.

“The system we initially put on alert is modest … not because the inherent capabilities of the sensors and interceptors themselves are somehow deficient, but rather because we will have a small quantity of weapons,” he said.

The scientists’ analysis argues that adding another 20 interceptors would not significantly increase the chance of success. For example, if the system were to engage a five-missile attack using interceptors each having a 10-percent kill probability, then firing 20 interceptors instead of five would decrease the probability of at least one warhead getting through from 99.99 percent only to 99.5 percent, the study says.

Only with a high kill probability is the benefit of additional interceptors significant, the analysis says. At a 50-percent kill probability against five missiles, for instance, firing 20 interceptors would give only a 28-percent chance of one missile getting through while firing five would give a 97 percent chance, it says.

“Because the system cannot counter threats that employ unsophisticated countermeasures, the kill probability will almost certainly be low. Consequently, more interceptors are largely irrelevant to system effectiveness,” it says.

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