China would have to calculate that the U.S. would be more willing to risk an escalation of conflict in the Taiwan Strait with a partial missile shield in place. And according to all estimates, China would lose a conventional war against Taiwan, even if it did manage to severely damage the island's economy. That calculus discourages China from belligerent behavior. So even though NMD is not aimed at depriving China of any nuclear deterrent, it would have important benefits in restraining its behavior and enhancing the security of East Asia. The firing of dummy warheads into the sea off Taiwan in 1995 and '96 was an indication that China is prepared to use violent means to retake the island.
Deterrence is a live issue.
Since sending aircraft carriers to Taiwan in 1996, the Clinton Administration has done little to dispel Chinese overconfidence. Pressing ahead with NMD would be a useful corrective, as is holding on to the possibility of deploying a theater missile defense in Taiwan. It's encouraging that State Department negotiator John Holum used this possibility in Beijing last week in response to the threat of medium-range missiles now being positioned on the coast of Fujian province. Far from showing why the U.S. shouldn't deploy missile defenses, Premier Zhu's protestations were a good indication that missile defense can change China's behavior. America and its allies in Asia will likely need such protection.