São Tomé and Príncipe becomes 176TH country to ratify CTBT

São Tomé and Príncipe has ratified the Comprehensive Nuclear-Test-Ban Treaty (CTBT), raising the total number of ratifications to 176, bringing Africa one step closer to universalisation.

The Central African state is a party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and a signatory to the African Nuclear-Weapon-Free Zone, referred to as the Treaty of Pelindaba. Its ratification of the CTBT highlights the country’s role as a strong supporter of the nuclear non-proliferation and disarmament regime.

The ratification took place on 22 September 2022 during the 77th session of the UN General Assembly High-level week in New York.

The ratification was welcomed by Robert Floyd, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) “as a further demonstration of São Tomé and Príncipe’s commitment to global peace and security.”

He further stated, “This is a proud moment for Central Africa and an inspiration for others, providing momentum for the Treaty’s universalisation and entry into force.”

“I am looking forward to enhancing the Organization’s cooperation with São Tomé and Príncipe so the country can enjoy the full benefits of Treaty membership,” he added.

The CTBTO head made an official visit to São Tomé and Príncipe's capital in April 2022. During his trip, Floyd met with officials who played a crucial role in the country’s ratification process, including President Carlos Manuel Vila Nova, Prime Minister Jorge Bom Jesus, President of the National Assembly, Delfim Santiago Das Neves, and Defence Minister, Lieutenant Colonel Jorge Amado.

"In addition to preventing lasting damage to the environment, human health, and vulnerable local communities that nuclear testing inevitably brings, a ban on nuclear testing is one of the most useful tools to prevent the spread of nuclear weapons. The CTBT is thus a critical element in the global effort to prevent the spread of nuclear weapons and promote nuclear disarmament,” said Izumi Nakamitsu, UN Under-Secretary-General and High Representative for Disarmament Affairs.

São Tomé and Príncipe's ratification means adherence to the CTBT is now universal in Central Africa and is further evidence of Africa’s strong leadership in nuclear non-proliferation and disarmament. It also highlights the continent’s contributions to ending nuclear testing to advance global peace and security.

São Tomé and Príncipe is the sixth country to ratify the Treaty during its 25th anniversary year, and the third African country to do so this year along with The Gambia and Equatorial Guinea.


The CTBT bans all nuclear explosions everywhere, by everyone, and for all time. Adherence to the Treaty is nearly universal, with 186 State Signatories and 176 ratifying states. However, to enter into force, the Treaty must be ratified by all 44 States listed in its Annex 2, for which eight ratifications are still required.

The CTBTO has established an International Monitoring System (IMS) to ensure that no nuclear explosion goes undetected. Currently, 303 certified facilities – of a total of 337 when complete – are operating around the world. The data collected by the IMS can also be used for a wealth of civil and scientific purposes, including disaster mitigation measures such as tsunami warnings and the tracking of radioactive releases from a nuclear accident.

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