He said the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is vital to ensuring that there are no more victims.

“I reiterate my call for all States that have not yet done so, to sign and ratify the Treaty, especially those whose ratification is needed for the Treaty’s entry into force,” Antonio Guterres said in a message marking the International Day Against Nuclear Tests that falls on August 29.

In a world of rising tensions and divisions, the UN chief said, their collective security depends on signing and ratification of the treaty. “It’s also essential to advancing nuclear disarmament.”

Guterres said the International Day against Nuclear Tests marks the closing, in 1991, of the nuclear test site in Semipalatinsk, Kazakhstan, the largest in the former Soviet Union.

More than 450 tests took place there, with impacts still being felt decades later.

“But this observance also has a broader message. It commemorates all victims of nuclear tests, anywhere they have been conducted. Affected communities have yet to fully recover from the environmental, health and economic damage,” he said.

Guterres said honoring those victims requires bringing nuclear testing to a permanent end. “Yet, an effective and legally-binding prohibition remains one of the longest unfulfilled goals of nuclear disarmament.”

He said the CTBT is a central pillar of international efforts, but despite being widely supported – with 184 signatories and 168 ratifying States – it has not yet entered into force, more than 20 years after its adoption.