20 February 2024

European Nuclear Weapons

Europe’s Nuclear Ambitions and the Constraints of International Law

After Donald Trump’s announcement to withhold US military support in case of an attack on a NATO member by Russia under certain circumstances, a discussion has been sparked on whether Europe itself should have their own nuclear weapons for nuclear deterrence. However, given the progress in the legal framework of nuclear non-proliferation and nuclear disarmament, European nuclear weapons would violate international law.

European Nuclear Weapons – An Old Idea

The idea of shared European nuclear weapons is quite old. In 1957, France, West-Germany, Italy, the Netherlands, Belgium and Luxembourg founded the European Atomic Energy Community (Euratom). While the main purpose of this Community is to promote the development of nuclear energy in Europe, Euratom was also intended to serve another purpose: A European nuclear weapon. In 1957, only the US, the Soviet Union and the UK possessed nuclear weapons. To facilitate the production of nuclear weapons, France, Italy, and Germany intended to share resources and knowledge to develop a European nuclear weapon. This idea was sacked with the election of Charles de Gaulle as French president and his decision to unilaterally pursue a nuclear weapons program in 1958.

What are the options?

There are several scenarios on how European nuclear deterrence could look like. First, an obvious scenario would be that France puts European Member States or the EU as such under a nuclear umbrella similar to the US’s nuclear sharing with several NATO members. Given the small number of French nuclear weapons (around 300) compared to the giant Russian arsenal (around 6000), the deterring effect of the French arsenal would be limited. Thus, a French nuclear umbrella could include the commitment by the EU or some European countries to financially contribute to the expansion of the French nuclear arsenal. A second option would be a genuine European nuclear weapon controlled by an EU chain of command. Such an approach reminds of the never established European Defence Community in the 1950s.

Option 1: A French Nuclear Umbrella for Europe

France’s capacity to share its nuclear weapons is limited by the 1968 Nuclear Nonproliferation Treaty (NPT). According to its Article I, France is not allowed to transfer nuclear weapons with any recipient. The using of the word “recipient” includes not only states but also supranational organizations such as the EU. The signatories of the NPT are also not allowed to transfer the control of nuclear weapons to non-nuclear weapon states (i.e. every state that is not the US, the UK, France, Russia or China).

Nuclear sharing is allowed to a certain limit. Currently, the US has nuclear sharing agreements with Germany, Turkey, the Netherlands, Belgium and Italy. The US military stations a certain number of nuclear weapons in the respective host country, while the host country provides the required deployment technology, mainly fighter jets that are capable of transporting and dropping nuclear weapons. In this scheme, the final control remains within the US chain of command. Given the fact that nuclear sharing agreements preceded the NPT, NATO countries interpret the NPT in a way that the deployment of weapons in non-nuclear weapon states is compatible with Article I, as long as the final say remains within a nuclear weapon state. This interpretation, however, is the object of constant criticism by both non-nuclear weapon states (e.g. Mexico) and also nuclear weapon states (China).

However, such a sharing of French nuclear weapons would – in any case – be excluded with state parties to the 2017 Treaty on the Prohibition of Nuclear Weapons (TPNW). Within the EU, Ireland, Austria, and Malta are parties to this treaty. Under Article I of the TPNW, any support towards nuclear weapons is prohibited. Member states must not allow the stationing of nuclear weapons in their territories. Furthermore, the use or the threat of use of nuclear weapons, as well as assisting, encouraging or inducing such behaviour, is also forbidden. There is no scenario where Ireland, Austria or Malta could share nuclear with France without violating their obligations from the TPNW. While withdrawal from the treaty is possible, this requires “that extraordinary events related to the subject matter of the Treaty have jeopardized the supreme interests of its country” and only takes effect after one year according to Article 17. Similarly, those states could not vote for a financial contribution by the EU for the French nuclear weapons program. While these three countries do not constitute a blocking minority under Article 16(4) TEU, budgetary questions within the Multiannual Financial Framework require a unanimous decision by the Council pursuant to Article 312(2) TFEU.

Option 2: Genuine European Nuclear Weapons

The second option – genuine European nuclear weapons – might escape both the NPT and TPNW at first sight. The EU is neither party to the NPT nor the TPNW. There are also no accepted customary obligations similar to those included in the treaties which might bind the EU. However, there would be two limits: Previous decisions by the EU and the need to change the European Treaties.

The EU itself has committed itself entirely to the non-proliferation regime. In 2003, the Council of the European Union adopted its Common Position 2003/805/CFSP on the universalization and reinforcement of multilateral agreements in the field of non-proliferation of weapons of mass destruction and means of delivery. The objective of this Common Position is, inter alia, to promote universal adherence to the NPT (Article 1(a)). To that end, the EU promotes all objectives laid down in the NPT (Article 4). The central objective of the NPT is to stop the proliferation of nuclear weapons. Thus, the development of European nuclear weapons would go against this Common Position. Similarly, the European Council adopted the EU’s strategy against the proliferation of Weapons of Mass Destruction in December 2003, where it is laid out that the NPT “must be preserved in its integrity” (para. 6). Both the Common Position and Decision were reiterated in Council Decisions 2012/423/CFSP and 2023/654/CFSP. Supporting the NPT as the cornerstone of the nonproliferation regime is central to the European non-proliferation strategy and the Common Foreign and Security Policy (CFSP).

Furthermore, even if the EU were to reverse these decisions, the current scope of the Treaties would not allow for a military chain of command. While Article 2(4) TFEU gives the EU the competence to “define and implement a common foreign and security policy, including the progressive framing of a common defence policy”, the development or control of its own arms and weapons would exceed such a progressive framing. The CFSP “might lead to a common defence” following Article 24 TEU, however such a decision requires unanimity in both the European Council and the Council. However, states bound not only by the TPNW but also by the NPT would be prohibited from accepting a common defence which includes nuclear weapons. The TPNW clearly prohibits such a change in its Article 1, excluding Malta, Austria and Ireland from such a treaty change. All 27 Member States are bound by the NPT, which would also prohibit them from voting for a European nuclear weapon within the EU institutions. Non-nuclear weapon states are prohibited from controlling nuclear weapons both directly or indirectly. Given the influence of the Member States via the Council and the European Council, at least an indirect control of European nuclear weapons would exist. In addition to that, such a vote would be in contrast to Article VI of the NPT. This provision includes the obligation to “pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race”. Such an acceptance of a supranational organization outside the NPT to possess nuclear weapons would constitute anything but good faith towards the cessation of a nuclear arms race.


European nuclear weapons are illegal under international law. France cannot share its nuclear weapons with the EU since Austria, Malta, and Ireland are state parties to the TPNW. The legality of nuclear sharing agreements under the NPT with European countries on a bilateral basis is questionable. Similarly, the EU cannot decide to develop its own nuclear weapons. The current treaty regime would require unanimity, while the NPT and TPNW prohibit EU Member States from voting for such an extension. Only one option remains for European nuclear deterrence without the US involved: France could unilaterally declare that it is willing to use its nuclear weapons once a Member State invokes a mutual defence clause (Article 5 North Atlantic Treaty or Article 42(7) TEU).

SUGGESTED CITATION  Sauter, Philipp: European Nuclear Weapons: Europe’s Nuclear Ambitions and the Constraints of International Law, VerfBlog, 2024/2/20, https://verfassungsblog.de/nuclear-weapons/, DOI: 10.59704/e59f32931316cdbc.

One Comment

  1. Rüdiger Sauerkraut Fri 5 Apr 2024 at 20:34 - Reply

    What happens if the EU acquires either a Nuclear Weapons Program or a Nuclear Shield (in any ways), despite the laws in the way? Like if it would just ignore the laws in place? What would be the consequence?

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