NATO Does Not Need Another Nuclear Sharing Arrangement

As NATO allies move toward the two percent defence spending benchmark, the question is not just how much they spend, but what they are investing in, and whether those choices ultimately strengthen or undermine the Alliance’s security environment. France’s emerging “advanced deterrence” doctrine raises that question directly. In a 2 March 2026 speech, President Emmanuel Macron outlined an expansion of France’s nuclear posture, including increasing warheads and the potential stationing of strategic forces in allied European countries.

For a doctrine meant to deepen nuclear deterrence across Europe, it may instead produce the opposite effect, cutting against NATO’s strategy and fuelling a renewed arms race. France’s deterrence has long relied on a careful balance between transparency and ambiguity, but its new features risk increasing nuclear uncertainty. The decision to stop disclosing the size of its arsenal reduces transparency and undermines a key confidence-building measure. The doctrine also envisages the possibility for France to conduct a “nuclear warning” against a state adversary to “restore the logic of deterrence”. While this was already part of the previous doctrine, the definition of the country’s vital interests is now more vague, which makes it difficult to contemplate in what scenario such a strike could occur. Rather than reinforcing deterrence stability, those measures increase the risk that a crisis could escalate through misperception, and the probability of a use of nuclear weapons.

Toward a Second Nuclear Umbrella

President Macron argued that the “advanced deterrence” doctrine would be a distinct effort, complementary to NATO’s nuclear posture. It builds on a process of Europeanizing nuclear deterrence, which started in 2020, when he stated that France’s interests extended to Europe. However, this speech took it to the next step by envisaging nuclear arrangements that could include, in the medium term, temporary deployment of strategic air forces in countries including Poland, the Netherlands, Greece, Sweden, Denmark, Germany, and the United Kingdom. 

While France would retain sole control over those forces, those agreements will include nuclear information sharing and the participation of these allies in joint nuclear deterrence exercises, starting with Germany. This could be described as a new form of nuclear sharing arrangement, which represents a major shift in the French doctrine, and NATO as a whole. Indeed, this would be the first time France actively includes its allies in its nuclear deterrence activities, creating a second nuclear umbrella in Europe, alongside the American one. In doing so, it risks moving beyond complementarity with NATO’s posture and toward a parallel deterrence framework.

France’s Past Nuclear Divergence from NATO 

From the outset, France’s nuclear posture has set it apart within NATO, a divergence that dates back to when the Alliance was headquartered in Paris. In 1966, Charles de Gaulle withdrew France from NATO’s integrated military command, prompting the Alliance to relocate its headquarters to Brussels. This decision reflected a longer-standing view. After the Second World War, de Gaulle was not willing to rely on the American umbrella, fearing it could compromise France’s sovereignty. In 1959, he told U.S. President Eisenhower that he could not trust future administrations to protect France in the event of a nuclear attack. Frustrated by U.S. refusals to share nuclear technology, France ultimately rejected NATO’s nuclear sharing arrangements and pursued an independent path. 

This legacy of nuclear independence has long set France apart, but the current shift risks extending that divergence in ways that could reshape the Alliance’s deterrence framework. Since then, France has remained the Alliance’s only fully sovereign nuclear power, rejoining NATO’s integrated command in 2009 but remaining outside its nuclear planning structures.

At the same time, France’s nuclear forces remained deeply involved in the transatlantic security strategy. In the 1974 Ottawa Declaration, the country pledged that its independent nuclear force de frappe or “strike force” would still contribute significantly to the Alliance’s overall security. Since then, France continued to strengthen its assurances to its allies regarding its role as a nuclear deterrent. The 1995 Chequers Declaration, issued jointly with the United Kingdom, affirmed that a threat to France’s vital interests would be considered a threat to the United Kingdom’s, reinforcing the European contribution to NATO’s deterrence posture. Crucially, this contribution remained aligned with NATO’s broader deterrence framework, rather than operating alongside it.

Deterrence Without Escalation

NATO describes itself as an inherently “nuclear Alliance”. It relies heavily on the so-called American nuclear umbrella, which France initially tried to separate itself from. The U.S. currently stores around 100 tactical warheads across Europe, including in Belgium, Germany, Italy, the Netherlands, and Türkiye. Member states of NATO have shown continued political and financial support for the Alliance’s nuclear activities. 

In October 2025, this was demonstrated through the annual nuclear deterrence exercise Steadfast Noon, involving 70 aircraft from 14 Allied countries. NATO’s deterrence posture rests on a clear premise: it is “defensive, proportionate, and fully in line with its members’ international commitments.” Its 2022 Strategic Concept frames the role of nuclear weapons accordingly, as tools to preserve peace, prevent coercion, and deter aggression. The 2012 Deterrence and Defence Posture Review reinforces this logic, emphasizing that any use of nuclear weapons in the Alliance context remains extremely remote, underscoring its fundamentally non-aggressive stance. France’s emerging approach departs from this logic of restraint.

Eroding Transparency, Proportionality, and Non-Proliferation

The expansion of France’s nuclear arsenal is framed as meeting thresholds “strictly consistent” with operational needs. In practice, this is difficult to sustain. France already possesses 290 nuclear warheads, most of them being ready to be delivered at any moment through oceanic or aerial forces if the President gives the order. Together, they amount to an estimated total yield equivalent of 2,600 times the bomb that was dropped on Hiroshima. 

France also has one of the most modernized nuclear arsenals. The strategic oceanic forces were equipped last year with new-generation M51.3 missiles. Each of these missiles can carry multiple independent TNO-2 warheads with a yield of 100 kilotons and a range of 9,500 kilometres. Taking stock of the existing capabilities of French deterrence, a rise in these numbers will not serve any operational effectiveness nor be consistent with the principle of strict sufficiency, but will represent a dangerous contribution to the renewed arms race.

The advanced deterrence aims at disseminating French nuclear capabilities in Europe, which raises serious questions under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). Its Article I prohibits nuclear‑weapon states from transferring nuclear weapons to any third party directly or indirectly, while its Article VI commits all parties to pursue disarmament in good faith. The NPT already faces a structural crisis, marked by the erosion of arms control frameworks and the adoption of more assertive nuclear postures. France’s new strategy risks deepening this trend by increasing distrust between nuclear-weapon states and others. Rather than strengthening Europe and NATO’s security, it further weakens the legal and normative framework that has long constrained nuclear competition.

Strengthening Europe Without Nuclear Expansion

If strengthening NATO’s European pillar means weakening arms control and blurring non‑proliferation norms, then the price is too high. Other paths exist to strengthen Europe’s deterrence within the Alliance, particularly through conventional forces. With an already strong French nuclear deterrence and an uncontested American nuclear umbrella, Allies should focus their efforts on strengthening European strategic autonomy. This requires €800 billion in investments in the next four years according to the European Commission’s 2025 White Paper for European Defence. 

Other measures that improve interoperability and support joint procurement, such as the €150 billion Security Action for Europe (SAFE) program, offer a more coherent and responsible path. The program, which has also drawn support from partners across the Atlantic, including Canada, enables members to access long-term European Investment Bank loans to develop shared conventional defence capabilities.

This also requires a renewed commitment to arms control, non-proliferation, and disarmament. France has previously played a constructive role in advancing nuclear security, from ratifying the Comprehensive Nuclear-Test-Ban Treaty in 1996, to unilaterally reducing its arsenal in 2008, and more recently supporting efforts toward a Fissile Material Cut-off Treaty.

The future of Europe and NATO’s security will not be built by multiplying nuclear arrangements, but by reinforcing the conventional and legal foundations of collective defence. The challenge is not to expand deterrence, but to create stable and responsible security conditions.