Since the 2002 Report, the United States and other Nuclear Weapon States have shown that they can maintain their nuclear arsenals and, in the cases of Russia and China, modernize them under a testing moratorium.

Advances in monitoring technology and capability since the 2002 Report (discussed in Chapter 2) have only made the prospect of evasive nuclear explosion testing more challenging.

The committee judges that, in addition to testing below detection levels, only two other evasion measures, mine masking and cavity decoupling, warrant serious discussion. The committee found no evidence of any new technical developments that would facilitate these evasion scenarios. The use of mine masking as an evasion strategy is challenging because the seismic monitoring of mining regions has improved and because the limitations of mine masking are better understood. With regard to decoupling as an evasion strategy, there is little new technical information since the 2002 Report. The challenges described in that report to a would-be evader attempting to decouple the seismic signal remain pertinent today. A more detailed technical discussion of evasive testing is presented in Appendix E.


It is important to be clear about what will and will not be technically affected by the CTBT. The CTBT bans nuclear-explosion testing but does not proscribe other activities for maintaining or even expanding a State’s overall nuclear capabilities. As a result, the United States has been able to sustain its nuclear stockpile under the test moratorium that has been in effect for nearly two decades, and to develop science-based tools that ensure the capability to use the results of the substantial U.S. test history in future work on nuclear weapons. It is reasonable to expect (and indeed the record shows) that other advanced weapons States will also use science-based approaches in maintaining and possibly adapting their nuclear weapons. Such activities may be quite extensive, but under a test ban, weapons deployable with confidence will be limited to designs that fall within the range of previously tested designs.1

Here we present a synopsis of how the four other Nuclear Weapon States (NWS) under the NPT are maintaining and to some extent modernizing their stockpiles of nuclear warheads and delivery systems. Among these four States, Russia has nearly an order of magnitude more nuclear warheads than the United Kingdom, France, and China combined. Of the four countries, Russia, the United Kingdom and France have signed and ratified the CTBT; like the United States, China has signed but has not yet ratified.


Efforts to modernize and reform Russia’s Armed Forces have been ongoing for most of the period following the end of the Soviet Union. The role and structure of Russia’s nuclear arsenal have been part of these general military modernization efforts. Russia continues to maintain its national nuclear weapon design laboratories at Sarov and Snezhinsk and to upgrade research facilities in line with a SSP-like program to maintain its nuclear stockpile. Russia also continues to maintain an active production complex.


1 There is also the possibility of acquiring information through espionage or transfer, but that is beyond the scope of this report.

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