China has had nuclear weapons for over 30 years, but they only have a dozen or so missiles that can deliver them to the United States. Until the Soviet Union fell apart, this was not a big issue. The Soviet Union was seen as the major danger and China's shorter range missiles could reach much of the Soviet Union. Now America is seen as the major foe and China is working hard to upgrade it's ICBMs and build nuclear submarines that can carry shorter range ballistic missiles to North American coastal waters. For all practical purposes, China can hit a few American cities with nukes. This would result in a U.S. response that would obliterate China, brings thousands of years of Chinese civilization to a fiery end. This is why China insists that America not build ICBM defenses. While the U.S. system is meant to stop a small attack from a small (and clearly suicidal) state, these defenses would also stop any Chinese ICBMs for some years to come. While China is unlikely to choose national destruction by firing nukes at America, it is felt that just having the possibility to do this provides a powerful diplomatic weapon. Actually, this "weapon" has already been used when a Chinese general publicly commented; "is America willing to trade Taiwan for Los Angeles" (meaning that U.S. coming to the defense of Taiwan during a Chinese attack could result in one of those Chinese ICBM's hitting one or more U.S. cities.) For the moment, Chinese nukes are more effective when used by their diplomats.