Senator Dianne Feinstein has written an opinion piece entitled"Let's Commit to a Nuclear-Free World," in this weekend's Wall Street Journal. In it she boasts of having blocked the Modern Pit Facility, Nuclear Test Readiness, and the Reliable Replacement Warhead. All three initiatives were part of folding the US Nuclear Umbrella in an orderly manner, rather than letting it collapse. I'll address these issues in the order Ms. Feinstein did.
The Modern Pit Facility was envisioned to re-manufacture "pits," which I assume is what Senator Feinstein meant by her use of the word "triggers." While it is true that we can re-use pits from dismantled nuclear warheads, we would need to re-manufacture those pits in order to build in certain "inherent" safety and security (anti-theft) features that the old pits don't have (because they were designed so long ago). Moreover, if we cannot re-manufacture pits, then we need to keep a lot of old pits around in case one or more of our adversaries decides to "sprint" to nuclear parity or superiority while we are trying to reduce our stockpile. The ability to re-manufacture would have enabled us to destroy many more of the old pits without fear that we would be leaving ourselves vulnerable to our adversaries. To state it as bluntly as I can, the Modern Pit Facility would have let us reduce our stockpile far below what we could risk without it. Failure to develop some kind of facility like it may set a limit on how low our stockpile can safely go.
Nuclear Test Readiness is part science and engineering, and part politics. The science and engineering is obvious: nuclear testing is the difference between confidence and certainty that our nuclear stockpile remains operational. The politics is that maintaining readiness makes it less attractive for an adversary to test so that they can watch us flounder for a few years trying to get ready to respond. That would erode confidence in the US stockpile and resolve, and might make some countries wonder whether they can really count on our nuclear umbrella, or whether they should build there own. Failure to maintain a reasonable readiness may thus contribute to nuclear proliferation - among our allies.
The Reliable Replacement Warhead is proof that nuclear weapons scientists don't know anything about marketing. What was really happening is that parts of the warheads in the current (so-called "Enduring") stockpile need replacement or fixing every so many years. We can maintain parts of the old Cold War weapons complex to service those parts, or we can redesign the parts to be manufactured and maintained by a smaller, complex that is cheaper, more secure, and more environmentally responsible to operate. Again, the idea behind the RRW and the MPF was to substitute a smaller, more responsive manufacturing complex for a bloated stockpile that included a lot of nuclear spare parts. Failure to move forward with these projects may again set a minimum number of nuclear warheads and spare nuclear components below which we cannot safely go - a roadblock on the path to zero.
That is to say, we need to be able to go from zero nuclear weapons to a lot very quickly. Otherwise, if we get to zero, our adversaries will use the opportunity to take advantage of us in ways that are both unpredictable and horrible to contemplate.
We may indeed get to zero nuclear weapons some day. But let us not do it on a path that leaves us and our allies naked before our enemies. Let us fold the US nuclear umbrella in such a way that it can be re-deployed quickly should international conditions warrant.
See also: Pitfalls on the Path to Zero