Implications for NATO of a ban on nuclear weapons
As a matter of international law, there is no barrier to NATO member states’ adherence to a treaty banning nuclear weapons. Concerns about the political implications of such a treaty for NATO ignore historical variations in member state military policy and underestimate the value of a ban on nuclear weapons for promoting NATO’s ultimate aim: the security of its member states.
Any discussion about the legal consequences of assuming new treaty obligations in the area of nuclear weapons must distinguish between the North Atlantic Treaty (a binding legal instrument), and the NATO Strategic Concept (a politically significant, but non-binding policy document). The North Atlantic Treaty is silent on the topic of nuclear weapons.
NATO’s nuclear capabilities
NATO does not possess any nuclear weapons of its own. 3 NATO member states (US, UK, and France) possess almost half of the estimated global nuclear weapons stocks, and a majority of the warheads currently operational.
NATO nuclear weapons policies
NATO nuclear weapons policy is articulated at both the inter-governmental level, and at the level of individual member states. It comprises the NATO Strategic Concept and other NATO policy documents, as well as a host of reservations, declaratory policies and military doctrines adopted by the Alliance’s individual member states. As a result, NATO nuclear policy is more complex and contested than is often assumed.
The NATO Strategic Concept accepts as a fundamental premise that nuclear weapons contribute positively to the security of the Alliance and its member states. It simultaneously recognises that nuclear weapons are problematic, and that such weapons should be sought eliminated. The document confirms NATO’s commitment to the goals of the Non-Proliferation Treaty, but cautions that NATO should remain a “nuclear alliance” for as long as nuclear weapons exist.
NATO seeks to ensure the “broadest possible participation of Allies in collective defence planning on nuclear roles, in peacetime basing of nuclear forces, and in command, control and consultation arrangements.” As a result, NATO’s non-nuclear weapons states (NNWS) actively participate in consultations and exercises involving nuclear weapons. Between 150 and 240 US nuclear weapons are forward-deployed in five European countries.
Policies adopted at national level
NATO member states have, since the early days of the Alliance, reserved the right to adopt independent national policies on nuclear weapons. Some of these restrict participation in the nuclear weapons activities of the Alliance, without restricting these states from participating in the work of the Alliance more generally. As indicated by the examples below, this right has been reserved by nuclear-armed and non-nuclear-armed states alike, suggesting that a precedent exists for allowing individual member states flexibility vis-à-vis policies agreed at the inter-governmental level.
- Deployment of nuclear weapons is prohibited in Denmark, Norway, and Spain (in peacetime), as well as Iceland and Lithuania (no distinction between war- and peacetime).
- Visits by nuclear-capable naval units are restricted in Iceland, Denmark and Norway.
- France does not participate in NATO’s arrangements for collective nuclear planning. Its nuclear weapons are not assigned to NATO, and its nuclear strategy is guided by national priorities, in the past often at odds with the preferences of other Allies.
- NATO’s claim to be a nuclear alliance rests upon its nuclear-armed members’ willingness to make their nuclear weapons available for collective defence arrangements. Any doctrinal changes in the UK and the US may as a result bear on NATO’s nuclear posture.
Member states’ legal obligations outside of NATO
Few instruments of international law in the area of nuclear weapons have been met with a unified NATO position. As explained below, NATO member states’ reactions to the Partial Test Ban Treaty (PTBT), Nuclear Non-Proliferation Treaty (NPT), and the Comprehensive Test Ban Treaty (CTBT) have varied considerably. The ratification of a treaty banning nuclear weapons by one or more NATO member states would not represent a substantial departure from this practice.
- Accession to and ratification of the NPT by NATO member states progressed according to varying national timelines, with France acceding as late as 1992.
- All NATO member states, with the notable exception of the United States, are parties to the CTBT. Ratification by the United States is necessary for the Treaty to entry into force. NATO member states have expressed disappointment at the US for failing to ratify.
- The vast majority of NATO member states are party to the PTBT. A notable exception is France. France tested nuclear weapons in January 1996, to the dismay of many NATO member states.