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CTBT Article IV: Verification

The International Monitoring System

Article IV is a key component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). It provides for a global verification regime—or global “alarm system”—to monitor all States Parties’ compliance with the Treaty’s provisions.

The main obligations in the CTBT are clear: all nuclear explosions are prohibited no matter whether they are conducted for military or peaceful purposes and no matter what yield they have. The verification regime thus has to be as tight-knit as possible, making it extremely difficult, if not impossible, to evade the prohibitions.

How this was accomplished during the negotiations of the Treaty in 1994-1996—both technologically and politically—was, according to Ambassador Jaap Ramaker of the Netherlands, who chaired the Treaty negotiations in their final year of 1996, “an example of diplomatic successes erected upon a bedrock of sound science”.

To read more about the negotiations of the Treaty, see Treaty History.

The creation of the CTBT’s verification regime is “an example of diplomatic successes erected upon a bedrock of sound science”.

Setting the stage

Wind noise reducing pipe array, equipment vault and the meteorological equipment of Infrasound station 44, Petropavlovsk-Kamcbatskiy, Russian Federation.

According to Ramaker, it was clear from the outset of the negotiations in 1994 that each and every one of the five nuclear weapon States – China, France, the Russian Federation, the United Kingdom and the United States – would not accept a test-ban treaty unless it included an international verification regime that would monitor the other States’ nuclear testing activities while not threatening their own national security.

In 1994 the Ad Hoc Committee established to negotiate the CTBT set up a working group on verification issues. This Working Group (Working Group 1) immediately initiated two years of intensive talks to hammer out what range of technologies (i.e. seismic and non-seismic) would be required to monitor nuclear testing in all environments—the earth, the seas, the air and, initially, also outer space.