But North Korea is unlikely to cooperate. It will do everything possible to suppress the defenses. The 1999 National Intelligence Estimate of the Ballistic Threat to the United States noted that any country capable of testing a long-range ballistic missile would "rely initially on readily available technology ‐ including separating RVs [reentry vehicles], spin-stabilized RVs, RV reorientation, radar absorbing material, booster fragmentation, low-power jammers, chaff, and simple (balloon) decoys ‐ to develop penetration aids and countermeasures."
Our anti-missile systems have never been realistically tested against any of these simple countermeasures. This is one reason that the Pentagon’s current director of operational testing is much more cautious in his assessments than missile defense program officials. "GMD has demonstrate a limited capability to defend the U.S. Homeland from small numbers of simple intermediate-range or intercontinental ballistic missile threats launched from North Korea or Iran," he reports. Moreover, it is impossible, he says, to "quantitatively assess GMD performance due to lack of ground tests" and "the reliability and availability of the operational GBI’s [Ground-Based Interceptors] is low, and the MDA continues to discover new failure modes during testing."