Liviu Horovitz and Lydia Wachs

France’s Nuclear Weapons and Europe

Options for a better coordinated deterrence policy

SWP Comment 2023/C15, March 2023

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DOI: 10.18449/2023C15

(English version of SWP‑Aktuell 7/2023)

Replacing the US nuclear guarantee with a French nuclear umbrella for Europe would face major political and logistical challenges. Nevertheless, given the growing uncertainty in Europe and Asia, the German government should consider scenarios and options that go beyond today’s deterrence architecture. Above all, it is conceivable that France would play a more visible complementary role to US extended nuclear deterrence. This could take various forms – from strengthened consultations to joint nuclear exercises. Even though any such steps are currently unlikely, it appears that now more than ever, US and European interests are aligning in a way that might allow for a better coordinated Western deterrence policy.

France’s Nuclear Weapons and Europe

Options for a better coordinated deterrence policy

Liviu Horovitz and Lydia Wachs

The Russian war against Ukraine and Moscow’s nuclear rhetoric have sparked a new discussion about deterrence in Germany. Against this background, political elites, especially those from the conservative spectrum, have repeatedly floated the idea of French nuclear reassurance for Europe. At the same time, there have been growing doubts in recent years about whether and for how long US nuclear security guarantees for Europe will remain in place. After all, despite the war in Ukraine, Washington is increasingly focusing on Asia.

Since the beginning of the Cold War, the European NATO allies have based their security on Washington’s security promises. It is for this reason that European security continues to depend ultimately on the credibility of the US government not only to wage a conventional war but, in extreme circumstances, to use nuclear weapons as well. Washington’s reaction to Beijing’s growing ambitions and, not least, increasing domestic political pressure in the United States have heightened doubts about long-term US engagement in Europe.

Accordingly, some German observers are repeatedly looking towards Paris. Two demands can regularly be heard. While some argue that France’s nuclear weapons should completely replace the US nuclear deterrent, others just want France to bolster US nuclear reassurance.

The European dimension

The German discussion notwithstanding, France’s proposals have always been much more limited. President Emmanuel Macron, for example, addressed two points in particular in a February 2020 keynote speech on French deterrence policy. He reiterated France’s solidarity with its European allies and stressed that France’s “vital interests” had a “European dimension”. During the Cold War, decision-makers in Paris had already pointed out that France’s security would be affected by any threat to the fundamental security interests of its neighbours. In recent years, France has concluded several bilateral security agreements with neighbouring states, including with Germany in 2019 as part of the Treaty of Aachen. What was new in Macron’s speech was the proposal to launch a “strategic dialogue” on the role of French nuclear weapons for the collective defence of the continent; for example, European partners might participate in exercises carried out by France’s deterrent forces. Such exchanges could help advance the development of a European strategic culture, Macron argued.

Subsequent clarifications by French officials have further underscored the limited nature of the French proposals. While Paris may well take its allies’ security concerns seriously, it still wants to retain full decision-making power over its nuclear arsenal. According to its official doctrine, French nuclear weapons strengthen European security by making the strategic calculations of adversaries more difficult. Any form of nuclear sharing, however, remains out of the question.

There are two main components to France’s ideas on nuclear cooperation in Europe. The first, and more important, has an educational imperative: French officials believe that France’s closest allies have neither a sound understanding of nuclear deterrence nor political backing for the necessary reliance on nuclear weapons for security reasons. Paris would like to help improve that understanding, not least in order to increase its own influence over NATO’s deterrence and defence policy.

The second component has to do with practical cooperation. Paris wants its close allies to participate in French nuclear exercises but it does not want them to play a key role; rather, they would carry out complementary tasks and capabilities only. The goal is not for partners to become indispensable for France’s nuclear deterrence but for them to become familiar with its processes.

In Berlin and other European capitals, these proposals were met with scepticism. It remained unclear whether Paris wanted to use its nuclear arsenal to advance European strategic autonomy at Washington’s expense or was merely seeking a complementary layer of nuclear reassurance within the alliance. During the Cold War and in the early 1990s, French strategists believed that these goals were mutually reinforcing: as long as the United States was committed to the European security architecture, Paris wanted to capitalize on its own nuclear potential to consolidate its position within a Washington-dominated international order, play a constructive role in NATO and promote security and stability in Europe. But at the same time France was preparing to assume more responsibility in the event of US retrenchment.

It is for these reasons that, apart from the few times when Washington displayed only moderate interest in European affairs, France’s neighbours have not been particularly inclined to accept Paris’s differentiated approach. As a result, little came of Macron’s offers to his allies to engage in nuclear cooperation. And amid all the doubts that arose under President Trump about continued US involvement in Europe and following Macron’s public criticism of NATO, German officials feared that if Berlin accepted Paris’s ideas, the US presence in Europe and within the alliance would only be further endangered.

Limited capabilities ...

Whether France would be able to replace the US nuclear umbrella depends on both political factors and technical capabilities. The main issue is that extended nuclear deterrence – i.e., the threat to use nuclear weapons to defend an ally and thereby run the risk of a nuclear counterattack – is not very credible per se. Ultimately, it is the adversaries and allies who decide on the credibility of deterrence. Academic scholarship suggests that there are three key factors: the political will and interests of the security provider, its military capabilities and the specific security environment.

The US government has always found it difficult to credibly signal its willingness to carry out nuclear threats in the event of limited aggression against an ally and therefore accept the risk of a limited nuclear attack against its own territory as the price for defending that ally. However, the importance of Europe in Washington’s global strategy and for the US-dominated world order has underpinned US security promises. Moreover, the US government has actively sought to prevent its security guarantees from being questioned. To this end, it has rejected a strategy of minimum deterrence, diversified its nuclear capabilities instead and engaged in nuclear sharing, which offers an institutional framework for consultations on nuclear policy.

Paris cannot simply circumvent Washington’s dilemmas. French experts argue that France’s geographical proximity and identity as a European nuclear power are fundamentally conducive to the credibility of an extended French deterrent. Nevertheless, given the current European strategic architecture, it is difficult for Paris to credibly claim that its interests in the European and international order are so important that it would accept the destruction of its own country in order to defend its allies. Even if France were to play a bigger role in the European political architecture, there would be still be basic geographical and economic factors standing in the way of credible French deterrence. Moreover, Paris’s policy towards Russia in recent years has raised fundamental doubts, especially among Central and Eastern Europeans, about whether France would put pan-European goals before its own national interests.

Such doubts cannot be dispelled by Paris pointing to its nuclear capabilities and deterrence doctrine. With some 300 nuclear warheads, France has a much smaller and less diversified arsenal than that of the United States. Most of its warheads are intended for submarine-launched ballistic missiles. A second, airborne component comprises nuclear-capable cruise missiles that can be deployed by a few dozen fighter aircraft. Unlike Washington, Paris also pursues a policy of minimum deterrence, which allows it to be able to inflict “unacceptable damage” on an enemy state. Thus, France’s nuclear weapons are directed not against a potential adversary’s nuclear forces but against its “political, economic and military nerve centres”. Furthermore, unlike the United States, France has only a few limited nuclear options that would allow for a more “gradual” escalation.

So, because its nuclear arsenal is rather small and not very flexible, Paris would have to respond to a Russian conventional attack against, say, the Baltic states by threatening the use of strategic nuclear weapons against Russian cities. And it would thereby have to accept a Russian nuclear retaliatory strike against French territory. Thus, even in a world in which the United States no longer provided nuclear deterrence for Europe, it is unlikely that France’s allies would unconditionally entrust Paris with their security.

... mean limited options

Nonetheless, if geopolitical developments should at some point lead Europeans to take a serious interest in French reassurance, various options would be conceivable in theory. All these options would generate new costs and new problems, however.

In one scenario, Paris would transfer decision-making power over French nuclear weapons to its allies, which would allow the latter to credibly threaten to use nuclear weapons in the face of aggression. But for this to happen, the French nuclear arsenal would have to be expanded and diversified. It would also require an institutional framework for joint command and control. Moreover, such a development would be tantamount to targeted proliferation. From today’s perspective, this would not only be incompatible with international law but would presumably also have significant consequences for security policy. First and foremost, however, there is the question of whether Paris would have any political interest in sharing decision-making power to such an extent and thereby losing its prominent role as a nuclear power.

As long as France does not relinquish control over its nuclear arsenal, the country’s security promises can be underpinned only by the establishment of an institutional framework that would give its allies some say over or, at least, an insight into French nuclear policy. One possibility would be an arrangement that resembles the current US nuclear-sharing system. But even that mechanism would lack credibility if France did not abandon minimum deterrence and significantly expand its nuclear capabilities. And what is more, even if France were to take such steps, credibility would still be primarily determined by the country’s political interests.

Any form of French nuclear sharing would require large investments by France and its allies. Above all, the options for limited escalation would have to be upgraded. While there is no doubt that France’s current arsenal offers the basis for such an expansion – given, for example, the airborne component mentioned above – today’s stockpile of nuclear warheads for air-launched cruise missiles is likely to be too small for extended deterrence. Enhancing France’s credibility to respond to limited aggression would likely require the production of nuclear warheads with lower yield.

For their part, the NATO states participating in this sharing mechanism would have to provide storage facilities. This would presumably mean a smaller outlay for the five states that are already involved in nuclear sharing and have the necessary facilities; but new host countries would first have to construct such depots. In addition, participating states would have to provide carrier aircraft. Using American F-35 fighters for French weapons would not be an option because of possible political differences and the lack of technical certification. Thus, new European fighter aircraft would have to be constructed for this task. The Future Combat Air System could be an option. It is currently being developed by France, Germany and Spain and is not expected to enter into service until 2040 at the earliest.

Finally, questions remain about both the institutional framework, and the command and control of such a sharing mechanism. Full institutional integration into NATO would be unlikely as long as the United States were part of the alliance. Therefore, a new institutional structure would be needed. Moreover, the decision-making and consultation process between France and the participating states would have to be clarified.

All in all, it would be both time-consuming and expensive to establish a credible French extended deterrent for Europe. The European NATO states have so far benefited not only from the nuclear but also from the conventional capabilities of the United States without having to make any significant contributions themselves. However, France, which is economically weaker than Germany, would not tolerate Berlin’s free-riding with respect to conventional capabilities.

French reassurance?

The European and international order would have to change fundamentally for French extended deterrence to replace the current US-centred arrangement. In such a scenario, two conditions would have to be met: (1) the United States would have to withdraw completely from Europe’s politico-economic architecture and as a guarantor of its security; and (2) the security threat in Europe would have to remain at the same level as today or even increase. And, as a consequence of these two conditions being met, the attitude of NATO states towards France’s role as a regional and nuclear power in Europe would have to change. However, it is very unlikely that these conditions will be met in the foreseeable future.

First, a US withdrawal from Europe is extremely improbable. To be sure, the transatlantic partners face numerous challenges as a result of China’s rise, the growing strength of isolationist and populist forces in the United States and various economic, technological and regulatory tensions. But Washington’s response to the Ukraine war has made clear that the United States will maintain its commitment to European security for the time being. And in the medium to long term, neither the Europeans nor the Americans seem to have many alternatives. In order to be able to carry on pursuing its global political, military and economic interests, Washington will continue to depend on cooperation with key European states. For their part, most European states would rather have the United States ensure the continent’s security and contain Russia’s ambitions.

Even a US government determined to reduce the cost of its European commitments would likely abandon extended nuclear deterrence only if it wanted to fully disengage from all its global commitments. Washington has long urged Europeans to invest more in their defence. But its main gripe is the lack of European conventional forces. With regard to nuclear deterrence, the United States still has considerable comparative advantages. While it will have to further modernize and expand its nuclear capabilities in the face of a resurgent Russia and a China expanding its nuclear arsenal, Washington already has a large and diversified nuclear arsenal of its own – one that is much better suited for extended deterrence than anything France or Europe could offer in the short or even medium term.

A future US president who questioned Washington’s security guarantees even more than Donald Trump would likely generate increased interest in complementary security mechanisms among many Europeans. However, based on the Europeans’ reactions to Trump’s policies, it is unlikely that they would be prompted by such a stance to make a serious effort to push alternative options, such as a French nuclear umbrella.

Second, it is impossible to predict how the security situation in Europe will evolve and how Eurasian relations might change in the event of a complete US withdrawal from the European order. On the one hand, Russia’s revisionist ambitions could force European nations to compromise on conflicting political, economic and security objectives in order to establish a credible deterrent against Moscow. On the other hand, it is just as plausible that France, Italy or Germany might be inclined to adopt a more cooperative approach towards Russia as a result of US retrenchment.

Third, it is equally difficult to assess whether security challenges would lead to a strengthening of the French role or to an overarching European nuclear capability. While it is likely that the above-mentioned challenges would render questions about different strategic cultures and attitudes towards security policy redundant, the politico-economic goals and interests of France and other European nations are without doubt difficult to reconcile. A drastically worsened security situation could induce France to assume more responsibility for its allies and to ensure that European security remains guaranteed – among other things, by nuclear deterrence. But that would probably mean that France would seek an enhanced political role in Europe in return. So far, the more transatlantic-oriented states in Central and Eastern Europe have been opposed to a more dominant role for France and are sceptical about French solidarity. However, if the United States were no longer to guarantee European security and stability – and thus the very basis of democracy and prosperity – the Central and Eastern European states might see a European system dominated by France and Germany as an acceptable alternative. In exchange, they would have to accept a subordinate role, but they would be able to carry on outsourcing responsibility for their security. Nevertheless, there is good reason to believe this will not happen: not only does France lack economic and military capabilities comparable to those of the United States, but it would also demand a higher price for its security services. Therefore, it is more likely that in such a scenario, Europe would decide on a joint nuclear option; and the United Kingdom’s nuclear weapons and strategic interests would play a significant role, too. But in this new era of European integration, the development of a European nuclear option would be not the first step but the last.

Strengthened cooperation in nuclear policy

It is highly unlikely that French nuclear weapons will play a decisive role in European security in the foreseeable future. The Russian war against Ukraine has shown that the United States remains the leading actor within the European security architecture. Therefore, as long as there is no drastic change in the situation either in Europe or in the United States, few Europeans are likely to question Washington’s role as the guarantor of the continent’s security. And this, in turn, means that Europeans will almost certainly refrain from taking steps that could politically endanger the extended US nuclear deterrent. Nevertheless, given today’s changing strategic environment and the implications for European defence policies, it may be possible to take limited steps. Two considerations are particularly relevant here.

On the one hand, Moscow’s nuclear rhetoric in its war against Ukraine has led to growing interest among many European states to upgrade nuclear deterrence. As a result, they may become increasingly motivated to align themselves more closely with France. The fact that for the first time, Paris has shown willingness to participate in more robust troop deployments on NATO’s south-eastern flank, thereby tacitly moving closer to the US “tripwire strategy”, is likely to have a positive effect on the attitude of the Central and East European states.

On the other hand, given the Europeans’ growing interest in deterrence, it may suit Paris to emphasize the role its nuclear weapons play in Europe. Presumably, intra-European dynamics will also influence the French position on nuclear issues. With the European Sky Shield Initiative, Germany has set itself the goal of improving European air defence. However, this drive towards deterrence by denial contradicts France’s traditional prioritizing of deterrence by punishment, whereby the French rely primarily on their nuclear potential. Moreover, Paris fears that this German initiative could have negative consequences for European cooperation and defence industries and would only increase dependence on the United States. For this reason, French observers believe that Paris could try to put the brakes on Berlin’s plans by renewing its offers for a strategic dialogue and possibly expanding the scope of such talks. Macron’s restatement of his 2020 nuclear proposals at the Munich Security Conference in February 2023 may be a pointer in this direction.

Options and recommendations

Based on the above assessment, various options are conceivable. For them to succeed, the common goals would have to be (1) improved coordination of Europe’s deterrence policies, (2) an enhanced French role as a European nuclear power and the increased visibility of its nuclear options and (3) Paris’s allies having more confidence in French solidarity.

From today’s perspective, the most realistic and likely option is France playing a more important role in achieving a common European understanding of the requirements of nuclear deterrence. Putin’s nuclear threats have revealed that there is a lack of in-depth knowledge in Europe about nuclear strategy. Thus, many Europeans may welcome enhanced French efforts in this area.

At the same time, France could seek more intensive cooperation between all NATO states on nuclear issues. It would make sense to upgrade and institutionalize consultations on nuclear policy that entail French involvement; and NATO’s Nuclear Planning Group (NPG) would be the perfect framework for doing so. However, France would almost certainly refuse to participate in that framework. Until now, it has not been part of NATO’s nuclear command structure because of sovereignty concerns and thus participates neither in consultations in the NPG nor in the alliance’s nuclear exercises. It is true that since 2010 Paris has assumed a more proactive role with regard to nuclear issues within NATO and that some French experts consider France’s accession to the NPG unproblematic in technical terms. However, such a step would likely meet with massive domestic resistance, as many would see it as posing a risk to France’s special nuclear role and sovereignty, while parallel structures or bilateral formats would not be in the interest of the other NATO states. Thus, a more intensive nuclear dialogue would be conceivable only in the North Atlantic Council, where irregular meetings on general questions of nuclear deterrence already take place.

Finally, nuclear exercises are another area in which increased cooperation would be possible. Not only could military coordination between NATO allies be improved; France’s visibility and role as a European nuclear power would be underscored to the rest of the world – and especially Moscow. Even now, NATO states are taking part from time to time as observers in the “Poker” exercises, which the French air force holds four times a year. In addition, representatives of France have attended NATO nuclear exercises as observers. Such activities could be intensified and thereby pave the way for more far-reaching steps. First, they could be expanded to allow NATO states that do not possess nuclear weapons to occasionally play an active role in French exercises by providing certain conventional capabilities. Second, France and NATO could simultaneously hold nuclear exercises to send more powerful strategic signals to Moscow. Third, France could station nuclear-capable fighter aircraft at allied bases. This would be a sign of solidarity with the allies and could make Moscow’s strategic calculations even more difficult.

These options notwithstanding, the Franco-German dialogue on nuclear issues is currently at an impasse: Paris seems to expect a response from Berlin following Macron’s 2020/2023 proposals, while Berlin considers those proposals too vague and is unclear about Paris’s thinking going forward. To break this impasse, German officials could approach their French counterparts. This would especially make sense if, in the heightened threat situation, the German government wanted to emphasize European nuclear deterrence, including France’s potential, or improve bilateral relations and, in the medium to long term, European security policy as well. Moreover, an open-ended exchange could help to promote mutual understanding for different ideas, expectations and positions: not only could it serve as a counterweight to the repeated calls in the German media for French reassurance; it could also pave the way for a more differentiated European strategic scenario planning.

However, Berlin would have to ask itself what concrete goals it would be pursuing through bilateral nuclear cooperation and what costs it would be prepared to bear. Among other things, Paris would probably want Germany to publicly acknowledge the importance of the French nuclear arsenal for European security and cut back its involvement in disarmament initiatives, especially the Treaty on the Prohibition of Nuclear Weapons. While Berlin might have to pay a domestic political price for agreeing to such steps, this could be outweighed by political, military and strategic advantages, such as participation in French nuclear exercises. It is also conceivable that Berlin would use a dialogue to explore longer-term possibilities for France to play a more significant role in NATO’s nuclear structures. Ultimately, however, it is only an improved understanding of mutually shared interests that can lead to further joint steps.

Dr Liviu Horovitz and Lydia Wachs are researchers in the International Security Research Division. The current paper is part of the Strategic Threat Analysis and Nuclear (Dis-) Order (STAND) project.