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 7 July 2026
at a ceremony at United Nations Headquarters in New York,
attended by David Nanopoulos, Chief of the Treaty Section at
the 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 Organization (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.
Robert Floyd, CTBTO Executive
Secretary
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Ambassador Va’inga Tōnē
reflected on the significance of the step.
For
Tonga, this is not simply a legal formality. It is a
statement of who we are and what we stand for. The Pacific
has felt the pain of nuclear testing. Ratifying the CTBT is
our contribution to ensuring that no one, anywhere, has to
go through that again.
Permanent
Representative of the Kingdom of Tonga to the United
Nations, Ambassador Viliami Va’inga
Tōnē
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.
Izumi Nakamitsu, UN High
Representative for Disarmament
Affairs
Tonga’s ratification is the
result of sustained engagement between States Signatories,
regional partners, the CTBTO and Tongan leadership over many
years.
This step reflects the strong commitment of His
Royal Highness Tupouto’a Ulukalala, Prince Regent of the
Kingdom of Tonga, to international peace and security, and
to the leadership it requires. Over the years, Floyd has met
regularly with senior officials and members of the Tongan
Government, including a mission to the country in May 2025,
when Secretary for Foreign Affairs Viliami Malolo reaffirmed
the Kingdom’s support for the CTBT and its engagement with
the Treaty. Ambassador Tone, who delivered the instrument of
ratification in New York, has also been a steadfast champion
of non-proliferation and disarmament.
At the 80th
session of the United Nations General Assembly in September
2025, the CTBTO head met with then-Prime Minister Aisake
Valu Eke. Earlier this year in April, the Executive
Secretary met with Ambassador Va’inga Tōnē on the
sidelines of the NPT Review Conference in New York, shortly
before Tonga confirmed its ratification.
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 Organization’s broader SEAPFE
grouping, which covers South-East Asia, the Pacific and
the Far East, just two countries have yet to
ratify.
Background:
The Comprehensive
Nuclear-Test-Ban Treaty(CTBT) bans all nuclear
explosions everywhere, by everyone, and for all time.
Adherence to the Treaty is nearly universal, with 188
signatories and 179 ratifying States. To enter into force,
the Treaty must be ratified by all 44 States listed in its
Annex 2, for which nine ratifications are still
required.
The CTBTO has established an International
Monitoring System (IMS) to ensure that no nuclear test
explosion goes undetected. Currently, 307 certified
facilities – of a total of 337 when complete – are operating
around the world, using four main technologies: seismic,
hydroacoustic, infrasound and radionuclide.
The data
collected by the IMS has also been used for disaster
mitigation such as earthquake monitoring and tsunami
warning, as well as research into fields as diverse as whale
migration, climate change and the prediction of monsoon
rains.
