Security assurances are commitments extended by nuclear-armed states to non-nuclear-weapon states (NNWS) regarding the non-use or threat of use of nuclear weapons. They are typically divided into two categories:
- Negative security assurances (NSAs): promises not to use or threaten to use nuclear weapons against NNWS, usually conditioned on the recipient's compliance with the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).
- Positive security assurances (PSAs): commitments to come to the aid of, or seek Security Council action on behalf of, a NNWS that becomes the victim of nuclear aggression.
The clearest multilateral expression came in UN Security Council Resolution 984 (1995), adopted in the run-up to the NPT Review and Extension Conference, in which the five recognised nuclear-weapon states (the US, UK, France, Russia, and China) issued parallel unilateral declarations on both negative and positive assurances. Each declaration carries its own caveats: China alone offers an unconditional no-first-use pledge against NNWS, while the others reserve the right to respond with nuclear weapons in certain scenarios, including attacks by a NNWS allied with a nuclear state.
Bilateral or treaty-based assurances also exist. The 1994 Budapest Memorandum provided assurances to Ukraine, Belarus, and Kazakhstan in exchange for their accession to the NPT as NNWS and the transfer of Soviet-era warheads to Russia — a precedent whose credibility was widely questioned after Russia's 2014 annexation of Crimea and 2022 full-scale invasion of Ukraine. Nuclear-weapon-free zone treaties (e.g., Tlatelolco, Rarotonga, Pelindaba, Bangkok, Semipalatinsk) include protocols through which nuclear-weapon states extend legally binding NSAs to zone members, though several protocols remain unsigned or carry reservations.
For NNWS, especially within the Non-Aligned Movement, the long-standing demand has been a legally binding, universal, and unconditional instrument on negative security assurances — a goal repeatedly raised at NPT Review Conferences and in the Conference on Disarmament but not yet realised.
Example
In 1994, the United States, United Kingdom, and Russia signed the Budapest Memorandum, providing security assurances to Ukraine in exchange for its accession to the NPT and the removal of former Soviet nuclear warheads from its territory.
Frequently asked questions
Negative assurances are pledges not to use nuclear weapons against non-nuclear states; positive assurances are commitments to assist a non-nuclear state if it is attacked with nuclear weapons.
Keep learning