Preserving the nuclear test ban after Russia revoked its CTBT ratification

Russia's withdrawal of its ratification of the Comprehensive Nuclear Test Ban Treaty in 2023 raised concerns about the possible end of the existing moratorium on nuclear explosions. But the moratorium continues to hold, largely thanks to the de facto norm against full-scale nuclear tests and the strength of institutional structures created by the treaty. Transparency of nuclear experiments demonstrated by the United States will be an important factor in upholding the moratorium, and Russia and China should be encouraged to be more transparent about their activities as well. Any disputes about the exact nature of their experiments and their adherence to the strict definition of a zero-yield nuclear explosion should not become reasons to question the value of the moratorium—or the ability of parties to verify and enforce the test ban once the treaty comes into force.