The Comprehensive Test-Ban Treaty (CTBT) is composed of three parts: Part I details the International Monitoring System (IMS), Part II focuses on the On-Site Inspections (OSI) component, and Part III is on Confidence-Building Measures (CBMs). The IMS conducts seismological, hydroacoustic, and other monitoring tests. The CTBT bans nuclear test explosions or any nuclear explosion in an effort for eventual international nuclear disarmament. As of 2016, eight Annex 2 states must either sign or ratify the Treaty for to enter into force. If, three years after the anniversary of its opening for signature the Treaty has not entered into force, a conference for the majority of the ratifying States may be held to examine the requirements not yet met. The Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) is an international organization with two organs: the Provisional Technical Secretariat (PTS) which coordinates with countries to develop and maintain an international network of monitoring stations and radionuclide laboratories, and the Preparatory Commission which is designed to help achieve the object and purpose of the Treaty.
Opened for Signature: 24 September 1996
Entry into force: Pending (Requires ratification by 8 additional states, including China, Democratic People's Republic of Korea, Egypt, India, Iran, Israel, Pakistan, and the United States of America)
Official Text: http://disarmament.un.org/treaties/t/ctbt/text
Status and Signatories: http://disarmament.un.org/treaties/t/ctbt
ACA Backgrounder: https://www.armscontrol.org/factsheets/test-ban-treaty-at-a-glance