Although they are clearly not coming right out and saying it, the quantity of individual launch-cell-installed ballistic missile interceptors deployed in Alaska

Although they are clearly not coming right out and saying it, the quantity of individual launch-cell-installed ballistic missile interceptors deployed in Alaska right now is clearly meant to deal with a threat from North Korea, not from Russia or China. The technology might exist but we would need something like a modern DEW line of many, many more of the same interceptors installed at bases spread throughout northern Canada to deal with a larger threat. It is assumed right now that the threat from Russia and China is met by the concept of mutually assured destruction, as neither Russia or China have a vast quantity of missile interceptors that could be truly relied upon to destroy hundreds of incoming US missiles. And the fact that US missiles can come from almost anywhere via submarine launch platforms.