Unfortunately much of the debate about the Comprehensive Nuclear Test Ban Treaty has focused on weather or not the US needs nuclear tests to maintain its nuclear arsenal or even expand it. This has pushed aside the important question of how the CTBT might increase or decrease risk of a nuclear conflict and replaced it with an ideological battle over whether the US should maintain a muscular military stance backed by nuclear weapons. Others even seem to view the CTBT as some kind of referendum on nuclear weapons. While I fully agree that nuclear weapons are an unfortunate development and that the US should retreat to a much reduced nuclear arsenal (enough to retain deterrence) these political questions should not distract us from the real implications of the CTBT.

In fact far from reducing the risk of nuclear conflict I think the CTBT actually increases this risk. The CTBT does little over the Nuclear Non-Proliferation Treaty (NPT) to further discourage proliferation. What it does do is increase the uncertainty over a countries nuclear arsenal and its effectiveness. As a quick game-theoretic style consideration reveals countries with only a 50/50 chance of having working nuclear weapons may in fact be far more dangerous than those countries with known nuclear capability. While one might think important concerns like this would be addressed by proponents of the CTBT but even relatively reputable advocates seem to have been distracted by the ideological battle. I will walk through the arguments below but ultimately I think it is a very bad idea to risk a greater likelihood of nuclear conflict just to make a statement.

Summary of CTBT

If you are unfamiliar with the CTBT a detailed summary of its contents is available from the Union of Concerned Scientists. A quick overview is that the CTBT bans “any nuclear weapon test explosion or any other nuclear explosion.” Although not defined in the treaty the US has interpreted this to mean that no test involving nuclear material can go critical. In addition to banning this activity the CTBT also sets up an international monitoring system of seismic, infrasound, radionuclide and hydroacoustic monitoring stations to verify compliance.

CTBT and Proliferation

The first point which should be noted is that the CTBT does nothing to prevent the proliferation of Hiroshima type fission weapons. Either nations already have such weapons or are precluded from developing them by the NPT. Any test discovered to be in violation of the CTBT would also be in violation of the NPT for a non-nuclear power. It seems wholly implausible that a state intent of violating the NPT and which felt a test was necessary for their nuclear program would be deterred because it was now violating two treaties instead of only one. More importantly explosive tests are simply not necessary to develop a simple fission device. Both the plutonium and uranium bombs developed in the 40s by the US worked the first time and there is every reason to believe other countries could duplicate this feat especially with the benefit of 60 years of scientific advancement.

Could the CTBT then prevent the development of fusion weapons (H bombs) by nuclear powers? Perhaps in theory but of the declared nuclear powers, i.e., the countries which wouldn’t be seen as violating the NPT by testing a weapon, only Pakistan and arguably India do not already posses fusion weapons. Given the willingness of these two countries to blatantly violate the NPT when they viewed it as necessary for their nuclear programs casts doubt on the ability of the CTBT to prevent them from developing fusion bombs. Moreover, if preventing escalation from fission to fusion devices is the benefit of the CTBT the same end could presumably be achieved by an NPT2 which committed fission powers not to escalate without incurring the dangers of the CTBT.

I’m unsure if preventing escalation to fusion weapons is even a desirable goal. In the present world climate I think it is a small scale nuclear exchange destroying several cities which is the greatest risk. Countries facing only a few fission blasts, perhaps not powerful enough to penetrate the bunkers protecting their leaders, may be much more likely to risk a nuclear conflict than those facing total annihilation and personal death from fusion weapons. Cold calculations like the one Von Neumann made advocating a first strike on the Soviet Union are much more aggressively inclined when a country is only facing a few relatively small fission devices. However, while the military impact of a few fission devices may be minor their humanitarian impact would not be. In the relevant situation of India and Pakistan it certainly seems plausible that both sides would be more willing to play a game of nuclear brinksmanship if they thought their opponent could only deploy fission bombs.

Still while we might debate about whether it is more dangerous to have India and Pakistan armed with only fission weapons or both possessing fusion devices we should all be able to agree the most dangerous situation of all is for them to both possess fusion devices while thinking the other one only has fission bombs or worse no working bombs at all. In general whenever we decouple the danger of nuclear war from its deterrent potential risk of a nuclear conflict radically increases. If India thinks that Pakistan has no credible nuclear deterrent it might risk a provoking military action. If India has miscalculated this could easily lead to a nuclear exchange neither side would have wanted.

This is the great danger of the CTBT. It is unlikely to further deter clandestine programs to develop nuclear armaments but it may create a climate unfavorable to any public demonstration of those arms. This could easily lead to situations where opponents underestimate each others nuclear capabilities with disastrous consequences. While nuclear threats may be unpalatable they are an infinitely preferable option to real nuclear exchanges. I know I would much rather see Israel detonate a nuclear device as a threat to discourage a muscular Arab neighbor than be deterred by the CTBT and be forced to use such a weapon for real in response to an invasion.

Other Concerns

So if the CTBT does increase the risk of a nuclear exchange in these situations is their any other benefit it might provide which could still outweigh these disadvantages? Looking at the arguments for the CTBT aside from the vague claim it would prevent nuclear proliferation we have already examined two other benefits are claimed. First that a ban on nuclear testing would protect the environment and secondly that it would halt development of a new round of nuclear devices by major nuclear powers.

No doubt nuclear testing poses and environmental hazard but could this environmental concern possibly be of the same import as the risk of a nuclear exchange? I think not. Even a small nuclear exchange would have such devastating human and environmental cost that just a slight increase in the risk of such an exchange outweighs any environmental concerns raised by testing. Moreover, the environmental impact of testing can be minimized by other treaties that demand countries test only in a responsible fashion without risking the harms of the CTBT.

Low and No Yield Weapons

Discouraging the development of new nuclear gadgets by the US and other major nuclear powers is the only serious benefit that might be claimed by the treaty. Low yield or neutron bombs are the last thing the world needs. Any devices that blur the boundary between nuclear and conventional weaponry pose a very real danger. However, it is exactly in these cases where the CTBT is the least enforceable. In fact given the way the US has construed the CTBT only to apply to supercritical events and the advances in computer modeling it is entirely possible that such devices could be developed without violating the CTBT at all.

There is already some debate as to whether the CTBT can detect militarily significant nuclear tests. As the opponents of the test point out low yield nuclear tests would be indistinguishable from high explosives and might be disguised as other types of conventional military testing. I don’t find their arguments persuasive as they apply to countries trying to develop normal fission or fusion weapons. However, if we are talking about places like the US with a considerable collection of test data trying to develop low or no yield devices the possibility of successfully hiding the seismic signal seems quite real.

While the CTBT does offer other non-seismic types of verification there is every reason these could be circumvented by an advanced power like the US. Even worse the non-seismic means of verification require detection by nearby monitoring stations. In large countries like the US, China and Russia this means stations located inside their own borders and a competent intelligence service could probably infiltrate or otherwise corrupt the small number of stations necessary to detect such a test. Ultimately I think the verification portion of the CTBT would be effective in stopping tests for the purposes of building conventional large yield nuclear weapons. However, precisely because these low yield devices might blur the line between conventional warfare and nuclear conflict it is reasonable to suppose an advanced power could disguise them as traditional military tests.

Still one might think the subterfuge and possibility of detection might discourage some nations from pursuing such programs, especially democratic countries like the US where public scrutiny or concerned citizens might bring such a program to light. This is true but once again these benefits and more can be achieved without the risks of the CTBT. If we are going to rely on public pressure and the moral force of the treaty to ensure compliance why not simply have the treaty ban exactly the type of device which concerns us. A treaty which prevented any nation from developing neutron bombs or other nuclear devices with yields under a kiloton would garner all these advantages plus prevent the construction of such weapons without testing. In fact it is quite possible that such a treaty already exists.

Conclusion

Apart from symbolism the benefits for enacting the CTBT are scant and can be achieved through other, less dangerous, measures. Unfortunately no one seems to want to talk about the real complicated effects such a treaty might have. Like Kyoto the CTBT has become an ideological litmus test preventing any detailed consideration on its merits. It is entirely possible my analysis is wrong and the CTBT reduces nuclear risk for reasons which haven’t occurred to me. However, what I am sure of is that nuclear war is too serious to make decisions about on the basis of emotion or simplistic analysis which blindly assumes any decrease in the expected number of working nuclear weapons is clearly good. I’m inclined to believe the CTBT on the whole increases the risk of nuclear war but whether or not you agree with me surely it would be idiotic to support this sort of treaty without a detailed analysis of these type of game-theoretic concerns.