[[Image:CTBT Participation.svg|right|400px|thumb| Participation in the Comprehensive Nuclear-Test-Ban Treaty {{legend|#5050ff|Annex 2, signed and ratified}} {{legend|#dcdc00|Annex 2, only signed}} {{legend|#ff5151|Annex 2, non-signatory}} {{legend|#000080|Not Annex 2, signed and ratified}} {{legend|#807f00|Not Annex 2, only signed}} {{legend|#800000|Not Annex 2, non-signatory}} ]] The contracting states to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) are the states that have signed and ratified the international agreement banning all nuclear explosions in all environments. Technically they will not be "parties" until the treaty enters into force, at which point these states will also be Member States of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), which comes into existence upon entry into force of the treaty. Non-contracting states are also listed, including those that are signatories and those are not. States Signatories are Members of the CTBTO Preparatory Commission. On September 24, 1996, the Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature. All five nuclear weapons states recognized under the Nuclear Non-Proliferation Treaty (China, France, Russia, the United Kingdom, and the United States) signed the treaty, with 66 other states following that day. Fiji became the first state to ratify the treaty on October 10, 1996. As of November 2024, 187 states have signed and 178 states have ratified the treaty. Most recently, Papua New Guinea ratified the treaty in March 2024. Signatures are received at the United Nations Headquarters in New York City by authorized representatives of the state. Ratification is achieved with the approval of either or both chamber of the legislature and executive of the state. The instrument of ratification serves as the document binding the state to the international treaty and can be accepted only with the validating signature of the head of state or other official with full powers to sign it. The instrument is deposited with the Secretary-General of the United Nations. Under the CTBT, there are 195 Annex 1 states which include a subset of 44 Annex 2 states. Nine Annex 2 states have not ratified the treaty: China, Egypt, Iran, Israel, Russia and the United States have already signed the Treaty, whereas India, North Korea and Pakistan have not signed it. The treaty will come into force only with the signature and ratification of the above Annex 2 states of the treaty, 180 days after they have all deposited their instruments of ratification.

Summary

Ratifying states

Signatory states

The following 9 states have signed but not ratified the treaty.

Non-signatory states

The following 9 UN member states, in addition to the UN observer State of Palestine, have neither signed nor acceded to the treaty.

Ratification progress

In 1998, India said it would only sign the treaty if the United States presented a schedule for eliminating its nuclear stockpile, a condition the United States rejected. In 2016, Israeli Prime Minister Benjamin Netanyahu said that its ratification was dependent upon "the regional context and the appropriate timing". The United States has signed the CTBT, but not ratified it; there is ongoing debate whether to ratify the CTBT. The United States has stated that its ratification of the CTBT is conditional upon: ":A: The conduct of a Science Based Stockpile Stewardship Program to ensure a high level of confidence in the safety and reliability of nuclear weapons in the active stockpile, including the conduct of a broad range of effective and continuing experimental programs. Proponents of ratification claim that it would: Opponents of ratification claim that: On October 13, 1999, the United States Senate rejected ratification of the CTBT. During his 2008 presidential election campaign Barack Obama said that "As president, I will reach out to the Senate to secure the ratification of the CTBT at the earliest practical date." In his speech in Prague on April 5, 2009, he announced that "[To] achieve a global ban on nuclear testing, my administration will immediately and aggressively pursue U.S. ratification of the Comprehensive Test Ban Treaty. After more than five decades of talks, it is time for the testing of nuclear weapons to finally be banned." An article in Bulletin of the Atomic Scientists describes how a North Korean underground nuclear test on May 25, 2009, was detected and the source located by GPS satellites. The authors suggest that the effectiveness of GPS satellites for detecting nuclear explosions enhances the ability to verify compliance with the Comprehensive Nuclear Test Ban Treaty, giving the United States more reason to ratify it.