Tonga Ratifies Nuclear-Test-Ban Treaty to Complete Pacific Universalization

The Government of Tonga ratified the Comprehensive Nuclear-Test-Ban Treaty (CTBT) during a ceremony at the United Nations Headquarters in New York on July 7, 2026. By becoming the 179th state to ratify the agreement, Tonga completed the universalization of the CTBT across the Pacific region. The diplomatic move followed years of engagement between Tongan leadership, regional partners, and the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), including a 2025 mission to Tonga.

Ambassador Viliami Va’inga Tōnē deposited the instrument of ratification, framing the action as a commitment to ensure that no one in the Pacific experiences the effects of nuclear testing again. The move occurs amid regional tensions after China tested a nuclear-capable missile with a dummy warhead in the Pacific, prompting accusations from Australia and New Zealand that the launch undermined regional stability. China defended the test as consistent with international law.

Tonga was already a member of the Treaty of Rarotonga and the Treaty on the Non-Proliferation of Nuclear Weapons. While the CTBT now has 188 signatories and 179 ratifying states, it will not formally enter into force until nine additional ratifications are secured from the 44 states listed in Annex 2. The process was driven by the commitment of Prince Regent Tupouto’a Ulukalala to international peace and security.