John Bolton Goes for the Big One – The CTBT

One of John Bolton’s objectives in becoming National Security Advisor is to destroy as many arms control treaties as possible. He convinced President George W. Bush to withdraw from the Antiballistic Missile (ABM) Treaty. President Donald Trump has now withdrawn from the Joint Comprehensive Plan of Action (JCPOA) with Iran and the Intermediate Nuclear Forces (INF) Treaty. Wrecking the Comprehensive Nuclear Test Ban Treaty (CTBT) would be the trifecta.

Bolton is a subtle man, and he is willing to work a long strategy. Here is a long explanation.



Negotiations on the CTBT began in 1994. President Bill Clinton signed it for the United States on the day it opened for signature in 1996, but the United States Senate has failed to ratify it. The treaty will go into force after 44 nuclear-capable states have ratified it. (Called “Annex 2 states” for where the list appears in the treaty.) The Annex 2 states that have not yet ratified it are the United States, China, North Korea, Egypt, India, Iran,  Israel, and Pakistan.

Nonetheless, states, including the United States, fund the CTBT Organization (CTBTO), which runs the International Monitoring System (IMS), a network of sensors to monitor whether nuclear tests have taken place. The IMS goes into action when an earthquake is detected in North Korea, for example. It publishes much of its data, but the complete files are available only to signatory nations.


The Accusation

Under the CTBT, nations are supposed to refrain from all nuclear tests. The United States claims that Russia, which has ratified the CTBT, has carried out low-yield nuclear tests. Although the United States has not ratified the CTBT, it maintains a moratorium on such tests, as it would under ratification.

The American statements, however, are not clear. Lieutenant General Robert P. Ashley, the head of the U.S. Defense Intelligence Agency (DIA) said, “The United States believes that Russia probably is not adhering to its nuclear testing moratorium in a manner consistent with the ‘zero-yield’ standard.” He also said “We believe they have the capability in the way they are set up” to conduct low-level nuclear tests that exceed the zero yield limit set in the CTBT. The United States has that capability too.

It is not clear whether Russia has actually conducted low-yield nuclear tests or what kind of tests they are. The test or tests could be of a low-yield nuclear weapon or much smaller hydronuclear tests.

The IMS can detect tests above 100 ton yield. That’s small for a nuclear weapon, but still a lot of destruction. Both Russia and the United States have, at times, been interested in nuclear weapons with yields that size. Another, slimmer possibility is that a nuclear weapon was tested in the cavity produced by an earlier underground test. That would “decouple” the blast and give much less of a seismic signal. Both of these possibilities seem unlikely because the NGOs that watch activity at the Novaya Zemlya test site have seen no activity that would support such tests.

If there was a test, it most likely was a hydronuclear test, whose yields are on the order of pounds of TNT, rather than tons. Which brings up the question of how the US knows there was a test.


Hydronuclear Tests

Full-up nuclear weapons tests are expensive and time-consuming. Subcritical tests or hydronuclear tests can give some information about how a nuclear weapon works without that level of expense and bother. A partial nuclear weapon assembly is set up and the chemical explosives detonated, with diagnostics designed to give the desired information. These experiments can be done in a metal container. More about them from Los Alamos and Livermore National Labs, the folks who do them in the US.

The test may give information on how plutonium acts during the chemical explosion, or how replacement parts behave, or safety information, or information useful in computer modeling of nuclear explosions. In a subcritical experiment, no nuclear yield is produced. In a hydronuclear experiment, some yield may be produced.

The tests are now done underground. American subcritical tests are done at the Nevada National Security Site, while Russia does theirs at their Novaya Zemlya test site. Here’s a video of one at the Nevada National Security Site.


Historical Hydronuclear Experiments

Subcritical and hydronuclear experiments have been used since nuclear weapons were first developed. A couple of their aspects are worth noting to give you some sense of them. During the test moratorium of 1958-1961, the one-point safety of a nuclear weapon design in the stockpile came into question. One-point safety means that a nuclear weapon will not give a nuclear yield if the conventional explosives are detonated at one point in an accident, for example. Hydronuclear tests were done underground at Los Alamos to explore the problem.

Most of the experiments gave a fission yield of one one-hundredth of a pound of conventional explosives. The last experiment gave a yield of four-tenths of a pound. Such amounts were a small fraction of the conventional explosives used. The experiments at Los Alamos were done at 50 to 100 feet underground.

The Soviet Union did many of their hydronuclear tests at the Semipalatinsk Nuclear Test Site, now in Kazakhstan. Some tests were done on the surface, some in metal containment vessels on the surface, and some underground. Many left plutonium metal where they had been carried out. in the early 2000s, a joint operation among Kazakhstan, Russia, and the United States recovered 100 kilograms of metallic plutonium and secured the testing sites so that recovery of any plutonium that might have been missed would be very difficult.


Subcritical and Hydronuclear Tests and the CTBT

The CTBT bans all nuclear explosions.

Each State Party undertakes not to carry out any nuclear weapon test explosion or any other nuclear explosion, and to prohibit and prevent any such nuclear explosion at any place under its jurisdiction or control.

This wording is very general. After much discussion, some of which was recounted on the Arms Control Wonk podcast, the Zero Yield standard was accepted. That is taken to mean any explosion produced by nuclear fission, so that hydronuclear tests are banned, but subcritical tests are not. CTBTO’s advisory group (GEM) issued this statement in regard to the current accusations:

In reaction to recent reports on alleged low-yield nuclear testing, the GEM stresses that all States Signatories share the “Zero-Yield” understanding of Article I of the CTBT, which clarifies that the CTBT prohibits all nuclear test explosions, whatever the level of energy released.

That means that the American tests of 1959-1960 would be banned under the CTBT, and probably many of the Soviet tests. The American accusation is that Russia has violated this zero-yield understanding.


Is Russia Doing Hydronuclear Tests?

We simply don’t know. CTBTO cannot detect nuclear yields below 100 tons, and hydronuclear test yields are usually under a pound. Watch the video above and listen to the slight ping as the assembly explodes. The only way the United States government might know is through signals intelligence or from someone who passed along documents.

The CTBT allows for on-site inspections. If the United States ratified the treaty, it could call for an on-site inspection. Jeffrey Lewis, in that podcast, suggested mutual inspections, with the Joint Verification Experiment (JVE) as a model.

In 1988, two underground nuclear tests were done – one at the Nevada Test Site and one at Semipalatinsk. A Soviet crew emplaced their instruments at Nevada to get readings and better understand the signs of an American nuclear test. Similarly, an American crew emplaced instruments for the test at Semipalatinsk. Additionally, by working together, the two sides built trust.

The analog for hydronuclear tests would involve groups from the countries being present, with their instruments at each other’s hydronuclear tests and working together to analyze the findings. Unlike the JVE, some instruments might be left at the other’s site, or a practice might be developed of having observers for most experiments.


Does It Matter?

In terms of usefulness for weapons design, there is little difference between subcritical and hydronuclear tests. A National Academy of Sciences panel found that such tests have largely been superseded by additional diagnostics and advanced computing. Even in 1987, when the report on the much earlier Los Alamos tests came out, Norris Bradbury, director of Los Alamos during the tests, observed that hydronuclear tests are not enough to support weapons development. In response to the recent claims, Siegfried Hecker, also a director of Los Alamos, said that such tests would not be “militarily significant.”

The most likely use of such tests now would be to make sure that replacement parts in refurbished nuclear weapons operate to specifications. Before a new nuclear weapons design would go into production and be added to the stockpile, at least two full-scale tests would be required.

And what if, as the worst case, Russia is somehow testing a new weapons design that they are confident enough of not to do full-scale tests? The United States and Russia both have produced several nuclear weapons designs within their 1500 or so deployed weapons and several thousand in reserve. Why does either side need new ones? Or why would we care if the Russians replaced some of the older designs with newer ones?


And Back To John Bolton

Bolton has no interest in improved verification and mutual visits as in the JVE. If the CTBTO cannot measure yields below 100 tons, that allows him to invoke protecting sources and methods to tell us why he can’t tell us his evidence for Russian violations. For Bolton, any violation is grounds for ending US connection with a treaty, as we see with the INF Treaty.

The Zero Yield interpretation gives Bolton ammunition. His argument will be we can’t tell if the Russians are violating the zero yield limit, so we must assume that they are and therefore repudiate Bill Clinton’s signature on the treaty. This would be bolstered by an implicit claim of intelligence that he can’t share.

In the last week or so, there have been tremors that Trump may be marginalizing Bolton, so perhaps Bolton will not have a chance to remove the US from the CTBT. Let’s hope.



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