CTBTO

The CTBTO Preparatory Commission was established in 1996 to prepare for the entry into force of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which bans all nuclear explosions on Earth — whether for military or peaceful purposes. Headquartered at the Vienna International Centre, it is funded by its States Signatories and led by an Executive Secretary; Robert Floyd of Australia took up that role in 2021, succeeding Lassina Zerbo.

The Commission's central task is to build and operate the International Monitoring System (IMS), a global network designed to comprise 337 facilities using four technologies:

• Seismic stations to detect underground shockwaves
• Hydroacoustic stations to monitor the oceans
• Infrasound stations to pick up low-frequency atmospheric waves
• Radionuclide stations (with certified noble-gas labs) to catch radioactive particles

Data flow in near-real time to the International Data Centre (IDC) in Vienna and on to States Signatories. The treaty also provides for on-site inspections once it enters into force, and the Commission trains inspectors and conducts integrated field exercises (notably in Kazakhstan in 2008 and Jordan in 2014).

The CTBT itself has not yet entered into force because it requires ratification by all 44 states listed in its Annex 2. Several Annex 2 states — including the United States, China, Iran, Israel, and Egypt — have signed but not ratified, while India, Pakistan, and North Korea have not signed. In November 2023, the Russian Federation revoked its 2000 ratification, though it remains a signatory.

Despite this legal limbo, the IMS has proven its operational value: it detected all six declared DPRK nuclear tests (2006, 2009, 2013, twice in 2016, and 2017), and its data are also shared with civilian users for tsunami warning, volcanic-ash tracking for aviation, and the Fukushima Daiichi radionuclide dispersion analysis in 2011.