Chicoms and Russians concerned abut missile defense
...I think their fears are more about their own projections than reality. The US has zero desire to conquer China or Russia. It would be like a dog chasing a car and not knowing what to do with it once it was caught. I suspect their real fear is that they will not be able to intimidate their neighbors as easily. It is what they want to accomplish beyond their borders that troubles them about missile defense.
For the Russians, not to mention Pyongyang's Chinese backers, the deployment of U.S. antiballistic missile (ABM) technology around the world is becoming a bigger and bigger concern. The Kremlin's anxiety, on clear display in Europe over the past few years, has more recently come to include the Asia-Pacific as the United States wraps up its delivery of the Terminal High Altitude Area Defense system to South Korea. That these systems will extend the coverage of missile defense radars operated by U.S. allies to include Chinese and Russian territory is an obvious concern to Beijing and Moscow, since the systems will enable Washington to better track missile flights and tests in both countries. But their fears go far beyond these immediate consequences.
Instead, Russia and China worry that the United States' devotion to investing in ABM technology could severely undermine their nuclear deterrents in the long run. After all, the latest generation of ABM systems — which are fairly scarce as it is — are woefully inadequate for defending against the two countries' vast nuclear arsenals at present. But neither Moscow nor Beijing can afford to assume that it will stay this way forever. For one, ABM technology could easily continue to mature and spread worldwide. More important, however, ABM systems do not exist in a vacuum. Rather, they complement the United States' strike capability. Russia and China fear that if the United States continues to simultaneously improve its ABM and strike capabilities, it could gain the ability to withstand a Russian or Chinese nuclear response in the wake of a crippling initial U.S. blow.
The recent progress Washington has made in developing more precise nuclear weapons — and faster, hardier delivery vehicles to carry them — has only added to Russia and China's growing unease. On March 1, the Bulletin of the Atomic Scientists issued a report on the United States' pursuit of a new capability called "super-fuzing." This technology replaces the traditional fixed-height fuse of the W76-1 nuclear warhead with a variable, self-measuring fuse that greatly enhances a warhead's ability to explode exactly at the optimal height over its target. Coupled with sturdier and speedier delivery vehicles, more precise nuclear weapons would give the United States room to reduce the number of warheads it would need to send to destroy each Chinese or Russian missile in the event of an attack.