Gambit, consider the SM-3 missile. It's being deployed by the Japanese. Aside from that, virtually everyone in China's immediate vicinity has some type of BMD. The Indians can shoot down some number of ballistic missiles; the Chinese have their own anti-ballistic missile system, I'm sure the Russians have similar equipment. For the AShBM to be truly effective, even if we assume that it can both hit and kill its target, it would have to be built en masse.
Also, if you're familiar with nuclear doctrine; both the United States and Russia maintain a launch-on-impact policy. They won't launch in retaliation until they know they've been nuked, and they can get away with it because their SSBNs can launch long-range missiles for a robust second-strike capability.
Also, if you're familiar with nuclear doctrine; both the United States and Russia maintain a launch-on-impact policy. They won't launch in retaliation until they know they've been nuked, and they can get away with it because their SSBNs can launch long-range missiles for a robust second-strike capability.