"If, by some miracle, we were able to eliminate nuclear weapons," he says, "what we would have is a number of countries sitting around with breakout capabilities or rumors of breakout capabilities -- for intimidation purposes. . . . and finally, probably, a number of small clandestine stockpiles." This would make the U.S. more vulnerable...

There's another compelling reason for a strong U.S. deterrent: the U.S. nuclear umbrella, which protects more than 30 allies world-wide. "If we were only protecting the North American continent," he says, "we could do so with far fewer weapons than we have at present in the stockpile." But a principal aim of the U.S. nuclear deterrent is "to provide the necessary reassurance to our allies, both in Asia and in Europe." That includes "our new NATO allies such as Poland and the Baltic States," which, he notes dryly, continue to be concerned about their Russian neighbor. "Indeed, they inform us regularly that they understand the Russians far better than do we."

The congressional commission warned of a coming "tipping point" in proliferation, when more nations might decide to go nuclear if they were to lose confidence in the U.S. deterrent, or in Washington's will to use it. If U.S. allies lose confidence in Washington's ability to protect them, they'll kick off a new nuclear arms race."

Exactly.  As I have said for a long time, the genie was long ago released from the bottle and can't be put back in.  We can't "unlearn" this.  We will never eliminate nuclear weapons even if we, America, go down the path of unilateral disarmament.  In fact, it may well incentivize rather than deincentivize other nations from seeking to acquire their own capability. 

I disagree with President Obama on the need to negotiate a new START.  I think it is misguided and not well conceived strategically.  Even though I understand he is not eliminating our entire stockpile, so he obviously is not a completely naive idealist on the issue, the very fact that he wants to eliminate any of our deterrent capability is largely an exercise in futility.  It will rattle allies and not matter to the North Koreas and Irans of the world.  Consequently, what is the point, other than to make everyone feel better?

Best to learn how to continue to deter old competitors and extend deterrence in such a way that it will have an impact on new adversaries or those that may become such in the future.