The Comprehensive Test Ban Treaty
How the CTBT works, why it has never entered into force despite broad support, and the global monitoring system that can detect nuclear explosions anywhere on earth.
The Treaty That Never Entered Force
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature in 1996 and has been signed by 187 countries and ratified by 178. It bans all nuclear explosions, whether for weapons testing or any other purpose. Yet the treaty has never entered into force because of a unique provision: it requires ratification by all 44 states that possessed nuclear technology at the time of the treaty's negotiation (the so-called Annex 2 states).
Of the 44 Annex 2 states, eight have not ratified: the United States, China, Egypt, Iran, Israel (which signed but did not ratify), and India, Pakistan, and North Korea (which have not even signed). The US Senate rejected ratification in 1999, with opponents arguing the treaty was unverifiable and that the US needed to maintain the option of testing to ensure the reliability of its nuclear arsenal. China has signed but made ratification conditional on the US going first. This deadlock means the world's most important test ban treaty remains in legal limbo.