P5 NSA

P5 NSA is shorthand used in arms-control and nonproliferation circles for the negative security assurances given by the five nuclear-weapon states recognized under the Nuclear Non-Proliferation Treaty (NPT): the United States, Russia, the United Kingdom, France, and China. A negative security assurance is a pledge by a nuclear-weapon state not to use, or threaten to use, nuclear weapons against non-nuclear-weapon states.

The legal and political foundations of P5 NSAs are layered:

• UN Security Council Resolution 984 (1995), adopted unanimously on the eve of the NPT Review and Extension Conference, took note of unilateral NSA declarations issued by each P5 member and affirmed assistance to any non-nuclear-weapon state party to the NPT that becomes the victim of nuclear aggression.
• Each P5 state issued its own unilateral declaration with differing caveats. China's is the most categorical, including a no-first-use pledge and an unconditional NSA to non-nuclear-weapon states and nuclear-weapon-free zones. The US, UK, and France condition their assurances, historically reserving the right to respond with nuclear weapons in certain scenarios (e.g., attack by a non-nuclear state allied with a nuclear state, or involving chemical or biological weapons).
• Legally binding NSAs exist through protocols to nuclear-weapon-free-zone (NWFZ) treaties — Tlatelolco (Latin America), Rarotonga (South Pacific), Pelindaba (Africa), Bangkok (Southeast Asia), and Semipalatinsk (Central Asia) — though the P5 have signed and ratified these protocols unevenly and with interpretive declarations.

Non-nuclear-weapon states, particularly through the Non-Aligned Movement and the New Agenda Coalition, have long pressed for a single, legally binding, unconditional NSA instrument, arguing that the 1968 NPT bargain is incomplete without it. Discussions recur in the UN Conference on Disarmament and at NPT Review Conferences, but no consensus treaty has emerged. Critics also note that the P5's modernization programs and doctrinal ambiguity weaken the credibility of existing NSAs.