Skepticism about the verification and enforcement of CTBT was key to the Senate’s rejection of the treaty in 1999. CTBT proponents now often promote the notion that CTBT verification and enforcement problems have been solved, but they are mistaken. The history of arms control from the 1930s until today demonstrates that without strong verification and enforcement measures, some states will violate solemn treaty commitments, and will continue to do so even after being caught. As a result, all now agree on the importance of on-site inspections of suspect nuclear testing to verify CTBT’s restrictions. Yet the treaty’s provisions for on-site inspections would require a mini-U.N.-like assembly of 31 countries to approve an on-site inspection request following suspicious activities. It is not difficult to see that agreement by 31 diverse countries to allow on-site inspection of suspicious behavior would become a political football; permission could not be assumed even following detection of highly incriminating behavior.
In addition, detection is not the same as enforcement — an important point typically dismissed by CTBT proponents. While the CTBT’s International Monitoring System provides some impressive detection technology, the treaty lacks any serious enforcement mechanisms whatsoever. Without enforcement mechanisms, the ability to detect treaty violations is, to paraphrase Frederick the Great, like an orchestra without instruments.
But the problem with CTBT ratification is not simply that the hoped-for benefits are unlikely ever to be realized; there also are prospectively large risks for the United States and its allies. While the CTBT cannot prevent opponents from developing or taking steps to modernize their nuclear weapons, U.S. ratification could hinder our capability to modernize our nuclear weapons as necessary for deterrence purposes. The reason is that the CTBT does not contain a definition of what constitutes the nuclear testing to be precluded.
The United States holds to a “zero-yield” criterion, meaning that no sustained nuclear reactions can take place as part of a test. But other nations need not hold to the same scrupulous definition, and could allow very-low-yield nuclear reactions during tests. The U.S. “zero-yield” criterion could undercut our ability to develop new capabilities critical to deterring future threats, while opponents choosing a less rigorous testing restriction could conduct nuclear experiments that would provide important military and/or political advantages.
For this reason, CTBT ratification would close off a deterrence safety route that we may need to take, without providing a barrier against a range of threat developments that may drive us to seek that safety route. Ratification could erect a solid legal barrier to meeting future deterrence needs that cannot now be known with certainty. It would be compatible with the Obama administration’s policy not to develop any new U.S. nuclear-weapon capabilities — but not with prudent deterrence policy.
International relations are unpredictable, particularly with regard to the potential for the rapid development of severe security threats. Increasingly, technology spread, global communications, and cultural developments abroad have joined to make the United States the object of animosities and to shrink the security value of the great distances that separate us from most centers of serious threat. Technology spread, including chemical, biological, and nuclear weapons, and the means to deliver such weapons, has also increased the potential for unexpected threat developments and the lethality of otherwise second- and third-rate military powers. No one knows what types of nuclear weapons may be needed in the future to deter new threats, but they are not likely to be the ones we designed and built during the Cold War.