The International Monitoring System (IMS) consists of 321 monitoring stations and 16 laboratories built world wide. These 337 facilities monitor the planet for any sign of a nuclear explosion.

The IMS uses four complementary verification methods, utilizing the most modern technology available. Seismic, hydroacoustic and infrasound stations monitor the underground, the large oceans and the atmosphere respectively.

Radionuclide stations detect radioactive debris from atmospheric explosions or vented by underground or underwater nuclear explosions. Radionuclide laboratories assist radionuclide stations in identifying these radioactive substances.

To learn more, please visit the area on the four technologies.

IMS monitoring stations and laboratories will operate in 89 countries around the world. Establishing them poses engineering challenges unprecedented in the history of arms control. Many stations are located in remote and inaccessible regions of the globe.

Once established or upgraded and certified as meeting all technical requirements, monitoring stations and radionuclide laboratories are operated by local institutions under contracts with the CTBTO.

The building and operation costs of the facilities (except for auxiliary seismic stations) are paid for by the CTBTO.

To get a good overview of all the facilities and where they are located in the world, click here.