This principle appears to introduce a basis for the Russians to argue that there should be geographic limitations on the deployment of U.S. TMD systems.
According to this logic, since Russia faces a potentially enormous danger of attack from shorter-range ballistic missiles, it would be entitled to an enormous number of TMD systems.
On the other hand, since the U.S. faces no theater missile threats, its TMD capabilities would presumably be limited to overseas deployments and possibly just to those numbers and regions where U.S. forces are still forward-deployed.