Nuclear Deterrence After Ukraine

Russia's invasion of Ukraine has revived many questions about nuclear deterrence. Whatever the outcome of what could be a long war, the issues it has raised will not go away.

In 1994, Ukraine surrendered the nuclear weapons it had inherited from the Soviet Union in return for security guarantees from the United States, the United Kingdom, and Russia. But those guarantees turned out to be worthless, and because Ukraine is not a member of NATO, it is not covered by the extended deterrence of the US nuclear umbrella.

What about the former Soviet republics that have joined NATO? Would US extended deterrence actually work for Estonia, Latvia, and Lithuania, or for its allies in Asia? For deterrence to be credible, nuclear weapons must be usable. But if they are too usable, an accident or misjudgment could easily lead to a disastrous nuclear war.

To achieve an effective balance, we must consider the appropriate mix of nuclear, conventional, and other instruments, and then reduce the nuclear component whenever possible. For example, whatever the appropriate response to North Korea's growing nuclear arsenal may be, it should not include a reintroduction of the tactical nuclear weapons that President George H.W. Bush removed from the Korean Peninsula in 1991....