This expansion comes under a president who campaigned for “a nuclear-free world” and made disarmament a main goal of American defense policy.
Mind you, Mutual Assured Destruction is a dangerous path, and one we managed to negotiate only because we were lucky (and we were) and because we were careful (and we were). As a strategy, it only works with rational people (e.g., world powers with lots to lose) who might have irrational expectations that they will win in the long run, the rapid fall of imperialist Russia was helpful (I have seen blackboard talks on this as a mathematical result in game theory). This speed minimized the time we spent in the high-risk regions while transiting from MAD to where we were in the 1990's, but the political world has changed, and this President is finding it hard to toe a pedagogical line in the face of neo-realpolitiks.
Refs:
You can bring any calculator you like to the midterm, as long as it doesn't dim the lights when you turn it on. -- Hepler, Systems Design 182