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Policy brief | 4 December 2025

Tried and tested: Why the CTBT must be preserved

NPT CTBT EU NATO NPT Nuclear Security Nuclear Weapons Multilateral Arms Control, Disarmament and Non-Proliferation NPT Project ELN
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US President Donald Trump’s statement about the US resumption of nuclear testing has heightened concerns over a renewed arms race and the erosion of the global norm against nuclear testing enshrined in the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The CTBT already faces mounting pressures, and even a single test could trigger destabilising arms race dynamics and weaken the credibility of the Nuclear Non-Proliferation Treaty (NPT).

This new policy brief from the ELN’s Protecting the Nuclear Non-Proliferation Treaty project argues that sustaining the CTBT is a strategic imperative. The treaty reinforces the NPT by bolstering the nuclear non-proliferation norm and constraining the development of new nuclear warhead types. Undermining the CTBT would deepen divisions among NPT state parties, increase mistrust between Nuclear-Weapon States, and negatively impact long-term international security.

States Parties to the NPT, therefore, need to work together to strengthen the CTBT’s credibility and relevance to international security, and prioritise collective multilateral action over any perceived short-term security gains. There are concrete steps that can be taken to preserve and reinforce the test-ban regime, including:

  • All NPT Nuclear-Weapon States should refrain from a resumption of nuclear weapons tests. They should maintain and publicly reaffirm their unilateral testing moratoria while pursuing early ratification of the CTBT.
  • EU and NATO States should ensure consistent and resolute support for the anti-test norm, emphasising that any nuclear weapons test, by any actor, would trigger a unified and robust response.
  • All NPT states should reaffirm the CTBT’s centrality to the NPT, use all possible diplomatic channels to promote ratification of the CTBT, strengthen their political and financial support for the Comprehensive Test-Ban Treaty Organization (CTBTO), and support remediation measures and assistance for communities affected by nuclear testing.

Read the policy brief

The European Leadership Network itself as an institution holds no formal policy positions. The opinions articulated in this policy brief represent the views of the author rather than the European Leadership Network or its members. The ELN aims to encourage debates that will help develop Europe’s capacity to address the pressing foreign, defence, and security policy challenges of our time, to further its charitable purposes.

Image: Alamy, James Schaedig

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