Much of the world has been angered by North Korea's Jan. 6 nuclear test and its Feb. 6 satellite launch/ballistic missile test. Incredibly, China seems most bothered not by Pyongyang's disregard for Beijing's interests, its dismissal of international law or its contempt for the United Nations, but by the actions of other regional governments to protect themselves against North Korean blackmail and threats. In Chinese eyes, it is missile defense that threatens to destabilize Northeast Asia, not a belligerent and unpredictable North Korean regime.

For several years, the United States has pressed its Asian allies to adopt missile defense systems to protect them and local U.S. assets against missile attacks. There are several reasons a host government could be troubled by such a request. They could object to the price of the program, especially at a time of tight budgets and fiscal restraint. As governments try to adapt to myriad new security challenges they must ask if this is the best use of limited defense funds. Answering that question with confidence is made more difficult by studies that have raised doubts about the protection such defenses really provide.

Strategists counter that a missile defense system does not have to be 100 percent effective to work. A missile defense system must only force an adversary to question the effectiveness of his weapons, which undermines the certainty that he will achieve his objectives. That is the essence of deterrence. For North Korea, a country with limited resources and considerable doubts about its technology, a little uncertainty goes a long way toward nullifying its arsenal.