Tonga has ratified the Comprehensive Nuclear-Test-Ban Treaty (CTBT), becoming the 179th State to do so and completing universalisation of the Treaty across the Pacific region. For a part of the world deeply impacted by nuclear testing, it is a milestone long in the making.
The ratification was formalised on 07 July 2026 at a ceremony at United Nations Headquarters in New York, attended by David Nanopoulos, Chief of the Treaty Section, UN Office of Legal Affairs, Permanent Representative of the Kingdom of Tonga to the United Nations, Ambassador Viliami Va’inga Tōnē, and CTBTO Senior Liaison Officer, Charles Abechi Oko.
Robert Floyd, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO), welcomed the ratification.
“Tonga’s ratification is a proud moment for the Pacific and a meaningful contribution to the global effort to ban nuclear test explosions for good. The Kingdom has long stood on the right side of this issue: as a party to the Treaty of Rarotonga, as a consistent voice for non-proliferation and disarmament, and as a country that understands how nuclear testing has impacted this region. I am deeply grateful to the many Tongan officials and regional partners who worked to bring this moment about.”
Melissa Parke, Executive Director of the Nobel Peace Prize-winning International Campaign to Abolish Nuclear Weapons said: “We congratulate Tonga on its accession to the Treaty on the Prohibition of Nuclear Weapons.
“Tonga will be the 75th state party to the treaty, which has another 25 signatories. These 100 countries have taken the humanity-affirming and necessary decision to totally reject nuclear weapons. It is time the nine nuclear-armed countries and other states that endorse the use of nuclear weapons get on the right side of history by eliminating these weapons that are a constant existential threat to every one of us,” Parke said.
When depositing its instrument of accession to the TPNW, Viliami Vaʼinga Tōnē, Permanent Representative of the Kingdom of Tonga to the United Nations, stated that “for a Small Island Developing State, these treaty actions represent far more than the fulfilment of legal obligations. They reflect our deeply held conviction that lasting peace, international security, the protection and sustainable stewardship of our oceans, and the progressive advancement of nuclear disarmament are inextricably linked to the well-being of humanity and to the sustainable future to which we collectively aspire.”
UN High Representative for Disarmament Affairs, Izumi Nakamitsu, also underscored the Treaty’s importance.
“The CTBT is an integral part of the global disarmament and non-proliferation architecture. It embodies a simple but vital truth: nuclear tests must never be allowed, not even one,” said Nakamitsu.
Tonga’s ratification is the result of sustained engagement between the Tongan leadership, regional partners, and the CTBTO over many years.
Tonga is a party to the Treaty of Rarotonga, which established the South Pacific Nuclear-Free Zone in 1985, the second such zone in a populated area of the world, prohibiting the manufacture, stationing, and testing of nuclear explosive devices in member territories. Tonga is also a State Party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).
With Tonga’s signature and ratification, the CTBT now counts 188 States Signatories and 179 ratifying States. Within the Organisation’s broader SEAPFE grouping, which covers South-East Asia, the Pacific and the Far East, just two countries have yet to ratify.
