Legal Frameworks for Preserving U.S. Nuclear Deterrent Primacy in Transatlantic Security

Introduction

The evolving geopolitical landscape, marked by debates over European nuclear autonomy and shifting U.S. security commitments, necessitates powerful legal mechanisms to ensure the continuity of the U.S. nuclear deterrent as the cornerstone of global security.

FAF analyzes actionable measures for the U.S. and EU to codify enduring legal assurances that reinforce the primacy of the original U.S. nuclear umbrella while addressing emerging deterrence architectures.

Reinforcing NATO’s Nuclear-Sharing Agreements

Binding Commitments Under Article 5

NATO’s collective defense principle (Article 5) remains the bedrock of transatlantic security but lacks explicit nuclear deterrence codification.

I’ll be back. A supplementary protocol to the North Atlantic Treaty could mandate that:

Nuclear Planning Group (NPG) Decisions

Require unanimous consent for any member state’s development of independent nuclear capabilities.

Weapons Stationing

Legally bind the U.S. to maintain tactical nuclear weapons (B61-12 bombs) in designated NATO states unless all members agree to withdrawal.

Consultation Mechanisms

Establish a standing legal committee under the NPG to review compliance with nuclear-sharing obligations biannually.

The EU’s 2024 proposal for a “European Nuclear Dialogue” with France and the UK could be subsumed under NATO frameworks through Article 4 consultations, ensuring any intra-European deterrence initiatives remain subordinate to Alliance-wide strategies.

Modernizing Negative Security Assurances (NSAs)

Treaty-Based NSAs Under NPT Review

The 2026 NPT Review Conference presents an opportunity to transform political NSAs into legally binding commitments.

Key proposals include

Protocol to UNSC Resolution 984

Create a subsidiary treaty requiring nuclear-weapon states (NWS) to

Refrain from nuclear use against non-NWS except in response to WMD attacks.

Provide conventional military support to attacked non-NWS within 72 hours.

EU-U.S. Joint Declaration: Unilaterally extend NSAs to all states adhering to the Additional Protocol, with violation triggers including:

Hostile cyber operations against nuclear command systems.

Territorial annexations violate UN Charter Article 2(4).

The Budapest Memorandum’s failure highlights the need for enforcement teeth—such as automatic UNSC sanctions for NSA breaches—while avoiding its non-binding “political commitment” flaws.

Bilateral Assurance Treaties

Model U.S.-EU Mutual Defense Pact

Building on the U.S.-EU Covered Agreement (2021), a nuclear-specific pact could:

Deterrence Integration

Mandate EU member states to allocate 15% of defense budgets to NATO nuclear infrastructure (e.g., Dual-Capable Aircraft modernization).

No-First-Use Coordination

Legally synchronize U.S. and French/UK doctrines by requiring EU nuclear forces to mirror U.S. presidential release authority protocols.

Arms Control Linkage

Tie U.S. New START compliance to EU ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

This would institutionalize the “assurance gap” closure recommended by the RAND Corporation, ensuring European capabilities complement rather than compete with U.S. systems.

EU Defense Integration with Deterrence Safeguards

Incorporating NATO Primacy into EU Law

The proposed European Defence Union (EDU) could embed legal clauses requiring:

Subsidiarity Principle

EU nuclear initiatives are only activated if NATO’s deterrent credibility falls below 50%, as measured by annual Eurobarometer surveys.

Funding Restrictions

Prohibit EU budget allocations to nuclear weapons R&D without unanimous NATO NPG approval.

Transparency Mandates

Public disclosure of Franco-British nuclear stockpiles to the U.S. Strategic Command (STRATCOM) for integration into NATO planning.

France’s “strict sufficiency” doctrine would need to be amended to include NATO consultation requirements before independent nuclear deployments.

Multilateral Verification Mechanisms

Global Deterrence Compliance Commission (GDCC)

A UNGA-established body under Chapter VII authority could:

Monitor Assurance Compliance

Satellite surveillance of U.S./EU nuclear facilities with real-time IAEA data sharing.

Trigger Automatic Sanctions

Impose sectoral embargoes on states developing parallel deterrents outside NPT frameworks.

Certification System

Issue “Deterrence Compliance Certificates” necessary for accessing IMF crisis loans.

GDCC jurisdiction would extend to cyber and space-based threats, addressing emerging domains absent from traditional NSA regimes.

Conclusion

Legal Architecture for Deterrence Continuity

The U.S. and EU can jointly construct a three-pillared legal regime:

NATO-Centric Binding Protocols

Anchoring European deterrence initiatives to Alliance decision-making.

NPT-Based Enforcement Tools

Transforming NSAs into actionable treaties with automatic penalties.

Transatlantic Legislative Sync

Harmonizing U.S. and EU defense appropriation laws to prioritize NATO nuclear infrastructure.

Failure to institutionalize these measures risks fragmentation into competing deterrence blocs—precisely the outcome the 1994 Budapest Memorandum failed to prevent.

By legally enshrining the U.S. deterrent's primacy, transatlantic partners can mitigate proliferation cascades while adapting to 21st-century threats.