Nuclear Sharing

Nuclear sharing is a policy arrangement within the framework of the North Atlantic Treaty Organisation (NATO) that enables non-nuclear member states to participate in the planning, deployment, and potential use of nuclear weapons owned by nuclear-armed allies, primarily the United States. The arrangement forms a key component of NATO’s nuclear deterrence strategy and has been a central, though often controversial, element of transatlantic security policy since the Cold War. It reflects a balance between collective defence obligations and efforts to prevent the proliferation of independent national nuclear arsenals.

Historical Background

The concept of nuclear sharing emerged during the early stages of the Cold War. Following the formation of NATO in 1949, the United States maintained a monopoly on nuclear weapons among alliance members. However, as tensions with the Soviet Union intensified during the 1950s, NATO sought to strengthen its collective defence posture by integrating nuclear deterrence into its strategy.
In 1954, NATO adopted the Massive Retaliation Doctrine, which relied heavily on nuclear deterrence to offset the Soviet Union’s conventional military superiority in Europe. To reassure European allies and discourage them from developing independent nuclear capabilities, the United States began deploying nuclear weapons across Europe. By the early 1960s, the arrangement evolved into a more formalised system known as nuclear sharing, in which selected non-nuclear NATO members would host U.S. nuclear weapons and maintain dual-capable aircraft capable of delivering them under wartime conditions.
The policy was reinforced through the NATO Nuclear Planning Group (NPG), established in 1966, which provided a forum for consultation on nuclear policy and strategy. This helped maintain alliance cohesion and ensured that nuclear decision-making remained under U.S. control while allowing European allies a participatory role.

Structure and Mechanism

Under NATO’s nuclear sharing arrangements, several key components define the operational and political framework:

• Ownership and Control: All nuclear weapons involved in the arrangement remain under the ownership and control of the United States. The U.S. President retains ultimate authority over their use.
• Deployment and Storage: U.S. nuclear bombs—primarily B61 gravity bombs—are stored at secure military bases across several European countries, including Belgium, Germany, Italy, the Netherlands, and Turkey. These weapons are kept under joint security arrangements involving both U.S. and host nation forces.
• Delivery Systems: Participating host nations maintain dual-capable aircraft (DCA) such as the F-16 Fighting Falcon and the PA-200 Tornado, capable of delivering nuclear weapons. In peacetime, these aircraft operate under national control, but in wartime scenarios, they would come under NATO command structures.
• Training and Readiness: Pilots and technical personnel from host nations receive specialised training to handle, maintain, and deliver nuclear weapons. However, the weapons remain physically controlled by U.S. personnel until a political decision for release is made.

The arrangement thus allows for integrated operational planning and deterrence without transferring ownership or independent control of nuclear weapons, in line with non-proliferation commitments.

Legal and Political Context

Nuclear sharing has often been discussed in relation to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which came into force in 1970. The NPT distinguishes between nuclear-weapon states (NWS) and non-nuclear-weapon states (NNWS), prohibiting the transfer of nuclear weapons or control over them to NNWS.
Critics argue that NATO’s nuclear sharing arrangement appears to contravene Articles I and II of the NPT, which forbid such transfers. However, NATO and its member states maintain that the arrangement is consistent with the treaty. Their interpretation holds that the weapons remain under U.S. control in peacetime, and that no transfer of control occurs unless NATO is engaged in a defensive war—a scenario in which the NPT’s restrictions would no longer apply.
This legal interpretation has been widely debated but remains the basis for NATO’s continued implementation of nuclear sharing under the NPT framework.

Strategic Purpose and Deterrence Role

Nuclear sharing serves several strategic objectives within NATO’s defence policy:

• Deterrence and Defence: It reinforces NATO’s nuclear deterrence posture, signalling that an attack on any member state could provoke a nuclear response, thereby discouraging potential aggression.
• Alliance Cohesion: By involving non-nuclear members in nuclear planning, the policy strengthens political solidarity within NATO and ensures a shared sense of responsibility for collective defence.
• Burden Sharing: The arrangement distributes responsibilities among member states, both financially and operationally, supporting the principle of equitable defence contributions.
• Non-proliferation Incentive: By providing allied nations with access to nuclear deterrence under U.S. control, nuclear sharing has historically discouraged countries like Germany and Italy from developing independent nuclear weapons programmes.

The nuclear sharing arrangement is therefore viewed by NATO as a stabilising factor in European security, integrating nuclear deterrence into a collective defensive framework.

Modern Developments and Challenges

Since the end of the Cold War, the role of nuclear sharing has evolved amid changing security dynamics. The number of U.S. nuclear weapons stationed in Europe has significantly declined from approximately 7,000 in the 1970s to an estimated 100–150 B61 bombs today. Nevertheless, the arrangement remains a central component of NATO’s Deterrence and Defence Posture Review (DDPR).
The 2014 annexation of Crimea by Russia and subsequent tensions in Eastern Europe revived debates about the relevance of nuclear sharing. NATO reaffirmed its commitment to maintaining a “credible nuclear deterrent,” while modernising the B61 bombs to the B61-12 variant, which features improved accuracy and compatibility with next-generation aircraft like the F-35 Lightning II.
However, the presence of nuclear weapons on European soil continues to be controversial, with growing public opposition in countries such as Germany, Belgium, and the Netherlands. Critics argue that the policy increases the risk of nuclear escalation, undermines disarmament goals, and makes host nations potential targets in a nuclear conflict.

Non-NATO Nuclear Sharing Models

While NATO’s arrangement is the most established, other forms of nuclear cooperation have existed outside the alliance. For example:

• U.S.–Japan and U.S.–South Korea Security Alliances: These involve extended deterrence commitments, often described as the U.S. “nuclear umbrella,” though without the physical deployment of nuclear weapons.
• Russia–Belarus Nuclear Cooperation: Following the 2022 invasion of Ukraine, Russia deployed tactical nuclear weapons in Belarus, marking a significant development in nuclear sharing outside NATO. This move has been widely criticised as destabilising and reminiscent of Cold War-era deterrence practices.

These developments underscore the continued geopolitical relevance of nuclear sharing as a tool of strategic influence.

Criticism and Calls for Reform

Nuclear sharing has faced sustained criticism from disarmament advocates, non-proliferation experts, and some political leaders within NATO member states. The main arguments against the policy include:

• Violation of NPT Principles: Critics contend that the arrangement undermines global non-proliferation norms by maintaining nuclear deployments in non-nuclear countries.
• Security Risks: The presence of nuclear weapons in multiple countries increases the risks of accidents, theft, or terrorist access.
• Political Obsolescence: Some analysts argue that modern strategic deterrence can be maintained through long-range systems such as intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs), making forward-deployed weapons unnecessary.
• Public Opposition: Civil society movements and political parties in Europe have called for the removal of U.S. nuclear weapons, particularly in Germany and Belgium, where anti-nuclear sentiment remains strong.