From Paris With Love: Extending France's Nuclear Umbrella Over Europe

European extended deterrence needs, French nuclear capabilities, and credibility challenges

Picture: Élisyée

The withdrawal of the United States from European defense has major implications for nuclear deterrence on the continent.

The United States possesses the largest, most diverse, and most capable nuclear arsenal among NATO’s nuclear powers. Since the early Cold War, it has used this arsenal to extend nuclear deterrence over Europe and protect non-nuclear NATO states.

Without the United States, this extended deterrence arrangement ceases to exist in its current form. President Emmanuel Macron has offered to fill that gap by extending France’s nuclear umbrella over European states. In this post, I examine how well France and its nuclear forces can assume this role and the credibility challenges they face.

How the United States has projected extended deterrence

To understand if France can replace the United State’s nuclear umbrella, it is important to understand what the United States was able to offer its European allies in terms of its extended nuclear deterrence “product”.

The United States was able to credibly extend its nuclear umbrella over Europe by ensuring its nuclear arsenal fulfilled three key functions:

1. Damage limitation

2. Nuclear warfighting

3. Coercive nuclear use to escape conventional defeat

First, the United States was able to credibly assure its allies that, if necessary, it could not only retaliate on their behalf but also preemptively target and neutralize the Soviet, and later Russian, nuclear arsenal in a counterforce strike.

This was made possible by the sheer size of the U.S. nuclear deterrent—both in terms of warheads and delivery systems—as well as its advanced capabilities. The United States invested heavily in highly accurate delivery systems capable of delivering warheads with far greater precision than required for simple "city-busting" retaliatory strikes.

Regardless of the ultimate feasibility of such a damage limitation strategy, the mere prospect of it played a crucial role in convincing allies that the United States would not shy away from a nuclear conflict if deterrence failed.

Second, the United States credibly signaled to its allies that it could fight a nuclear war with the Soviet Union and later Russia at all levels, including at the non-strategic (sometimes referred to as "tactical") nuclear level.

This was possible because the United States has maintained options for nuclear warfighting below the strategic level, though the diversity of its non-strategic nuclear arsenal has significantly declined in the post-Cold War era—a shift that has been heavily debated in policy and expert circles in recent years.

Non-strategic nuclear capabilities played a key role in the United States' extended deterrence strategy by reassuring European allies that the United States had options short of either submitting to Soviet or Russian non-strategic nuclear use, which would have been unacceptable, or immediately escalating to strategic nuclear use, which would have been seen as non-credible.

This was also one of the reason why the NATO, under the leadership of the United States, shifted its military doctrine in the 1960s from “Massive Retaliation”—the idea that any Soviet attack in Europe would trigger immediate largescale nuclear use—towards “Flexible Response”—the idea that the United States retained warfighting options at all levels of conflict, including the conventional, non-strategic nuclear, and strategic nuclear levels.

Third, the American nuclear arsenal contributed to credible extended deterrence by offering the option of coercive nuclear use as a means to avoid conventional defeat.

In a conflict with the Soviet Union or Russia where NATO was losing, the United States, alongside its European allies, could credibly threaten to escalate from a major conventional war to a limited nuclear conflict.

This escalation served two key purposes. First, the introduction of nuclear weapons could potentially shift battlefield dynamics by halting or reversing Soviet or Russian advances. Second, limited nuclear use would immediately raise the risk of uncontrolled escalation, ultimately leading to full-scale nuclear war and mutually assured destruction—making continued hostilities unwise for both sides.

This threat was reinforced by the forward deployment of American nuclear weapons to Cold War frontline states, most notably West Germany. While no European state would have taken the decision to introduce nuclear weapons into a conflict lightly—especially if the war was fought on its own soil—a German chancellor might have done so if the alternative was outright conventional defeat.

By fulfilling these three functions, the United States was able to provide credible extended nuclear deterrence commitments to its European allies through its nuclear arsenal. Of course, the arrangement was not without flaws, and the fundamental question of whether the United States would ultimately be willing to "trade Hamburg for New York" remained a concern during and after the Cold War.

However, it is difficult to argue that this nuclear umbrella was not well-designed and carefully thought-out to fit an extended deterrence framework. While not perfect, it certainly played a role in complicating Soviet and later Russian military planning.

Can the French nuclear arsenal replace the U.S. extended nuclear deterrent?

The key question then is if the France can offer a better or at least equally good extended nuclear deterrent “product” to its European allies. Most likely, this is not the case—at least unless the French nuclear arsenal and doctrine undergo major changes, and as long as the perceived scope of the nuclear umbrella remains unchanged.

The French nuclear arsenal is insufficient in size and capability to offer meaningful damage limitation in the event of a nuclear conflict. Unlike the United States, France is essentially only able to retaliate on behalf of its allies, not to take preemptive action.

That might not be an issue for Belgium, Germany, or the Netherlands—countries geographically close to France. If their survival were threatened, France would likely face an existential threat as well, if not immediately, then in the near future. In such a scenario, large-scale nuclear use on their behalf is at least somewhat credible.

However, this credibility does not extend to states further from France, including the Baltics, the Nordics, Poland, and Romania. Here, the question of whether a French president would trade “Tallinn for Paris” becomes unavoidable.

In discussions with French officials and in Macron’s statements, I get the impression that the French believe they can bridge this credibility gap through their long-standing policy of strategic ambiguity—the idea that they will not specify when and how they would resort to nuclear use. Macron’s references to "vital European interests" without further clarification reflect this approach. However, it is difficult to see how such nuclear guarantees would be taken seriously north and east of Germany.

France, at present, is also unable to credibly signal to its allies that it could fight and potentially win a nuclear war with Russia at the sub-strategic level. France lacks both the arsenal depth and the arsenal diversity necessary to compete effectively with Russia in a non-strategic nuclear warfighting scenario.

This could put France and its European allies in a position where they are forced to either submit to Russian non-strategic nuclear use or escalate to the strategic nuclear level, an option that may not be seen as credible by allies.

A key issue here also lies in France’s nuclear doctrine. At present, French doctrine does not acknowledge the existence of a distinct non-strategic nuclear level, treating all nuclear use as strategic in its consequences. This doctrinal stance effectively prevents France from incorporating moew non-strategic nuclear options into its nuclear planning. While this was not a problem when French nuclear doctrine was solely focused on protecting French vital interests, it becomes a major issue if France attempts to extend its nuclear umbrella over other European states.

Finally, with some adaptations, the French nuclear arsenal could be well positioned to support coercive nuclear use as a means to escape conventional defeat, similar to the role played by the American nuclear arsenal. This would be especially true if French nuclear weapons were forward-deployed to countries facing an immediate threat of Russian invasion, much like West Germany during the Cold War.

This means that discussions about forward-deploying Rafale aircraft and ASMPA-R nuclear cruise missiles to Germany are somewhat redundant and do little to enhance the credibility of French extended deterrence. Germany is already relatively well covered by France’s strategic nuclear arsenal, as outlined above.

Instead, the focus should be on forward-deploying French nuclear capabilities to Estonia, Finland, Latvia, Lithuania, Poland, and Romania—the new frontline states in the confrontation with Russia. If this were to happen, and if French decision-makers could agree on joint authorization procedures with the leadership of these countries, it could significantly complicate Russian planning and strengthen nuclear deterrence in Europe amid U.S. withrawal.

How to get the French deterrent extended deterrence ready?

It’s important to emphasize that the above is an observation, not a critique of the French nuclear deterrent. France’s nuclear arsenal and doctrine were developed and evolved over decades with one primary goal: guaranteeing the independence and territorial integrity of France. In this respect, the French nuclear deterrent has performed well and remains entirely fit for purpose.

This stands in stark contrast to the American nuclear deterrent, however, which, since at least the 1960s, has evolved with an additional key objective in mind: making extended deterrence on the European continent a credible undertaking.

For the French nuclear arsenal to play a credible role in extended deterrence, it must evolve toward that function. In my view, this remains an overlooked point. Discussions often focus on what France can currently offer its allies and how receptive European states are to a French-led extended deterrence arrangement. However, for a credible French nuclear umbrella to emerge, the deterrent itself must first adapt to this role—something that only Paris can decide.

Evolving the French nuclear deterrent toward a damage limitation role would be politically highly controversial and likely financially unfeasible. However, France could adapt its nuclear arsenal and doctrine to provide additional options at the non-strategic nuclear level and forward-deploy some of its nuclear assets, ideally to frontline states.

In terms of material capabilities, this would likely require the development of lower-yield nuclear warheads, an increase in the number of delivery vehicles for non-strategic nuclear warheads, and ideally a diversification of delivery vehicles capable of carrying them. This could include gravity bombs and, ideally, short- to medium-range ballistic missiles. Of course, all of this takes time and cannot be implemented overnight, meaning there is no quick fix. There is also the question of who would fund such an expansion, with states like Germany, Italy, or Poland potentially contributing. However, the ultimate decision to invest in these capabilities rests with Paris.

Looking at doctrine, France would need to move away from strategic ambiguity. As a British diplomat once put it, "it only takes five percent certainty to deter your adversaries, but 95 percent certainty to reassure your allies." There is a lot of truth to this, in my view.

To compete at the non-strategic nuclear level, France would first have to acknowledge that such a level exists in the first place. In practice, this should not be difficult, as France—in my personal view, though I know some analysts may disagree—already operates within this framework through its "final warning" ASMPA-R employment, which I would define as serving a non-strategic purpose. As such, it may simply be a matter of formalizing what is already in place.

Lastly, one may argue that simply forward-deploying a limited number of ASMPA-R and Rafale aircraft to a country like Germany, without changing doctrine or evolving the arsenal, could still provide benefits, particularly from a political perspective. While I don’t disagree with this, I would argue that if the French nuclear umbrella is meant to be more than a symbolic gesture and actually contribute to credible deterrence outside of France, I don’t see how it can do so in its current form.