List of parties to the Comprehensive Nuclear-Test-Ban Treaty

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 February 2021, 185 states have signed and 170 states have ratified the treaty. Most recently, Cuba signed and ratified the treaty in February 2021.
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.
Eight Annex 2 states have not ratified the treaty: China, Egypt, Iran, Israel 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.
Signatory states.
The following 15 states have signed but not ratified the treaty.
Non-signatory states.
The following eleven 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:
Proponents of ratification claim that it would:
Opponents of ratification claim that:
On 13 October 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 5 April 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 25 May 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.