Neutralizing the Russian nuclear deterrent could be seen as the first step to allowing offensive moves against Russia, since the U.S. will have removed Russia's strongest shield against conventional invasion. Combined with extending NATO to Russia's borders, it is easy to see how that Russia would feel threatened by this on a grand strategic level.

We would never countenance Mexico joining the Shanghai Cooperation Organization, for instance, especially if China had the beginnings of a way to neutralize our nuclear deterrent.