An Expanded Nuclear Deterrent in Europe Without the United States?

The Ukrainian leaders’ gamble on Donald Trump’s about-face toward Moscow may well prove to be well-founded. After once again reaching out to Vladimir Putin, to no avail, the U.S. president has just sanctioned Rosneft and Lukoil, which account for half of Russia’s oil production. The delivery of Tomahawk cruise missiles is back on the table—the Pentagon has given its approval—and Russia’s nuclear posturing has pushed Trump over the edge; he is considering resuming tests in the Nevada desert. Clearly, the nuclear dimension of the war in Ukraine, in terms of rhetoric and posture, cannot be overlooked. What of the U.S. nuclear umbrella and the protection of Europe?

The “U.S. nuclear umbrella” is the common name for the United States’ extended nuclear deterrence in Europe, within the framework of the Atlantic Alliance (NATO). In the event of a large-scale attack on its European allies, the United States is committed to coming to their aid and responding, including with its nuclear weapons, with the aim of deterring the potential aggressor, i.e., inhibiting and preventing them from taking action. Immediately after the founding of the Atlantic Alliance in 1949, the first Strategic Concept stipulated that the alliance should “ensure the possibility of rapid strategic bombing involving the use of all weapons without exception,” in the same year that the USSR conducted its first nuclear test, thus ending the United States’ brief atomic monopoly (1945-1949).

Perpetuation and renewal of the United States’ extended deterrence

The U.S. extended deterrence, with its doctrinal framework of massive retaliation (the Dulles Doctrine, announced in 1954), was materialized by the deployment of U.S. nuclear weapons on European soil that same year. While the U.S. still enjoyed geostrategic insularity, as the USSR did not have air or ballistic delivery systems powerful enough to reach U.S. territory, the threat of massive retaliation on USSR territory in the event of military aggression in Europe was intended to counterbalance Soviet conventional superiority and negate the temptations it induced. The 1952 Lisbon Conference did not result in a sufficient increase in Allied conventional forces¹. In 1957, NATO’s SACEUR (Supreme Allied Commander in Europe) was integrated into the decision-making chain for the launch of nuclear weapons in Europe.

The development by the USSR of intercontinental ballistic missiles and, consequently, the end of American geostrategic insularity, signaled by the launch of the first Soviet satellite (the “beep-beep” of Sputnik on October 4, 1957), explain the abandonment of the doctrine of massive retaliation in favor of that of graduated response (the McNamara doctrine, 1962). There was heated debate among the Allies, particularly between France and the United States, as the adoption of this new doctrine raised fears that the latter were seeking to limit the hypothetical use of nuclear weapons to the Central European battlefield, without taking the risk of exposing their own territory to a Soviet nuclear strike. Nevertheless, NATO remained a nuclear alliance: launched in 1963, the Multilateral Force project failed two years later (it would have merged national components), but it led to a system of “nuclear sharing” and “dual key,” with Allied crews required to deploy American nuclear weapons. More nuclear resources were dedicated to extended nuclear deterrence (nuclear-powered ballistic missile submarines, strategic bombers and, even more so, tactical nuclear weapons).

At the same time, a Nuclear Planning Working Group (NPWG) was created, bringing together eight allied countries, including the FRG (Federal Republic of Germany). In addition to deterring the USSR and protecting the territory of NATO member states, this mechanism aimed to counter the nuclear proliferation feared by Washington (the doctrine of graduated response gave rise to this temptation even in the FRG). In 1966, when France expressed its desire to leave NATO’s integrated command, the NPWG gave way to a Nuclear Planning Group (NPG) open to all member states (France did not participate).

While the United States and the USSR were negotiating the limitation of the growth of strategic nuclear arsenals (SALT I in 1972; SALT II in 1979), Moscow’s deployment of intermediate-range nuclear weapons (the SS-20s, which were more accurate and intended for the European theater) provoked the “Euro-missile crisis”: European allies feared that this deployment would undermine the extended deterrence of the United States, causing a geostrategic decoupling between the two sides of the North Atlantic. The deployment by the United States of Pershing II ballistic missiles and Tomahawk cruise missiles reassured European allies of American security guarantees. Subsequently, the Washington Treaty signed in 1987 by the United States and the USSR on INF (Intermediate-Range Nuclear Forces), i.e., missiles with a range of 500 to 5,500 kilometers, eliminated this category of weapons².

In the post-Cold War era, NATO’s nuclear posture weakened, especially as political forces in Germany (Social Democrats, left-wing parties, and Greens) and elsewhere campaigned for a No First Use policy (a commitment by NATO and its members not to be the first to use nuclear weapons), or even for the withdrawal of the few American tactical nuclear weapons, known as “sub-strategic,” still deployed in Europe (see below). In 2009, while U.S. President Barack Obama was entertaining the idea of universal nuclear disarmament (Global Zero), Germany, Norway, Belgium, the Netherlands, and Luxembourg published a joint letter calling for the application of the Global Zero concept in Europe.

In contrast, the French and British governments pointed out that NATO is a “nuclear alliance” and must remain so. Russia’s aggression in Ukraine, beginning in 2014, contradicts this desire to relegate nuclear weapons to a secondary role in NATO’s deterrence and defense posture, especially as China modernizes and expands its own arsenal (1,500 nuclear warheads in the long term), not to mention North Korea’s nuclearization and Iran’s ballistic missile program. As things stand, NATO’s global deterrence relies on nuclear forces, conventional forces, missile defense, arms control, and non-proliferation (see the Madrid Strategic Concept, 2022).

NATO’s nuclear forces include an airborne component, fighter aircraft (Tornado and F-16s, currently being replaced by F-35s) armed with B61-12 “sub-strategic” gravity bombs (approximately 250 recently modernized bombs), stationed in five countries (Germany, Belgium, the Netherlands, Italy, and Turkey). Greece is also involved in NATO’s nuclear missions, and all other NATO member countries are likely to participate in support missions (fighters, radar aircraft, and other conventional means), known as SNOWCAT (Support of Nuclear Operations with Conventional Air Tactics). This system is complemented by U.S. strategic nuclear forces, the ultimate guarantee of Allied security. Added to this are the national nuclear forces of France and the United Kingdom, which are independent of NATO but whose contribution to “global deterrence” and the security of the Allies is recognized by the Ottawa Declaration (June 16, 1974) and regularly reiterated since then. In short, the extended nuclear deterrence of the United States to Europe is a strong and enduring reality.

Nevertheless, Donald Trump’s re-election as President of the United States in November 2024 and the direction of a U.S. foreign policy that struggles to find unity and coherence are jeopardizing the strategic credibility of this extended nuclear deterrence. Beyond his longstanding aversion to alliances, which he perceives as a scam, the U.S. president has long expressed a number of deeply-held beliefs against nuclear weapons, citing conversations within his family circle with a paternal uncle, a renowned physicist who warned him of their danger to global security³.

The outline of a hypothetical European deterrent

From a European perspective, current developments and the theoretical possibility of the United States leaving NATO, which would mean the end of extended nuclear deterrence and strategic decoupling between the two sides of the North Atlantic, are leading several European countries, notably Germany, Poland, and the Baltic states, to be concerned about a future European nuclear deterrent, provided jointly by France and the United Kingdom. Admittedly, developments in recent weeks have been rather favorable to the maintenance of the transatlantic geostrategic link, but we cannot ignore the fact that the United States is undergoing a kind of revolution with uncertain consequences. This is all the more true given that the opening of a new theater of operations in Venezuela, at a time when the U.S. military apparatus—from Europe to the Asia-Pacific region, via the Middle East—is under strain, could further change the situation.

In the event of a U.S. withdrawal from NATO, which is theoretical at this stage, the U.S.’s extended nuclear deterrence strategy, which benefits its European allies, would disappear, and U.S. nuclear weapons would be repatriated. Washington has not yet announced anything to this effect: the U.S. nuclear arsenal deployed in Europe and its foothills (in Turkey) has even been recently modernized. ⁴. Nevertheless, the turn taken by U.S. foreign policy during Donald Trump’s second term opens up a range of possibilities. In such a scenario, France and the United Kingdom would not need to provide additional guarantees to those offered by the United States (see Franco-British statements, consultation and strategic discussions between European allies), but rather an expanded nuclear deterrence strategy at the European level, replacing the former American hegemony. While we are not there yet, German, Polish, Baltic, and other leaders are taking the possibility of a U.S. withdrawal very seriously, even if the Atlantic summit in The Hague (June 24-26, 2025) has temporarily averted this scenario.

Two days before the latest German parliamentary elections, CDU-CSU leader Friedrich Merz, now chancellor, said he wanted to “discuss with the British and the French whether their nuclear protection could be extended to Germany” (ZDF, February 21, 2025). On March 5, the French president responded by agreeing to open a debate that he had previously sought to initiate (see Emmanuel Macron’s speech on deterrence, delivered at the Military Academy on February 7, 2020). Two days later, Prime Minister Donald Tusk affirmed his country’s interest in the issue before the Polish Sejm. On May 9, 2025, Paris and Warsaw also signed the Treaty of Nancy, which includes a defense clause consolidating those of NATO (Article 5 of the North Atlantic Treaty) and the European Union (Article 42, &7 of the EU Treaty). It would be up to Paris and London, closely linked on military and nuclear matters, to devise and conceptualize a European-wide deterrence doctrine capable of countering the Kremlin’s nuclear posturing and Russia’s aggressive sanctuary strategy. Paris and London could coordinate their SLBMs (nuclear-powered ballistic missile submarine) patrols in order to strengthen their permanent presence at sea, thereby ensuring the invulnerability of their deterrent capabilities⁵.

As the United Kingdom no longer has an air component to its nuclear deterrent, it would be up to France to deploy Rafale aircraft armed with nuclear missiles on the territory of willing countries, under bilateral agreements. These countries would participate in “logistical support for nuclear operations” (opening bases, silos, air defense, and in-flight refueling). Ultimately, a form of “nuclear sharing” could be envisaged, with a dual-key system: French nuclear weapons on German, Polish, or other aircraft, with the decision to use them remaining a national one, as is currently the case in NATO⁶. In short, the NATO mechanisms would have to be replicated, but without the United States, which would involve the creation of a European Nuclear Planning Group⁷. Far from being improvised, an expanded deterrent would require a solemn political commitment from participating countries and its inclusion in an overall strategic framework, with a strong conventional component, including strike systems deep within the theater of operations and an anti-aircraft/anti-missile defense system (see the German-European Sky Shield project, which, as it stands, does not have France’s approval)⁸.

Conclusion

Let us emphasize once again the hypothetical nature of this European deterrent, or more precisely, of an extension of French and British nuclear strategies to the European continent. The fact remains that such a prospect is part of the Europeanization of NATO and, more broadly, of burden sharing between the two sides of the North Atlantic (the famous “burden sharing”). This is all the more true given that the current situation seems to confirm the dawn of a new nuclear age, as French international relations expert Thérèse Delpech anticipated: she spoke of an era of strategic piracy, in which gestures intended to intimidate or even coerce (aggressive sanctuarization) would take on increasing importance.

Let us consider the facts: Russia is putting a “flying Chernobyl” (the Bourevestnik) into orbit for several hours, according to an American specialist; China is increasing its strategic nuclear arsenal, equipping itself with the means for an aggressive sanctuary strategy; Iran is continuing its nuclear program; and North Korea is developing its intercontinental missiles. In such a configuration, it will not be enough to display the calm of the old guard, recalling the strictly sufficient nature of national nuclear forces (those of France and the United Kingdom) and the virtues of deterrence, in the strict sense of the term.  If a European military pillar were to be established, it would need to have a nuclear component, which would be the cornerstone of the continent’s defense.

Addendum

Sky Shield Initiative: the European missile defense shield project

Six months after his speech on the Zeitenwende (Bundestag, February 27, 2022), German Chancellor Olaf Scholz presented the idea of a European missile defense shield for which Germany would assume responsibility, without prior consultation with France (speech in Prague, August 29, 2022). Two months later, Berlin announced the launch of the European Sky Shield Initiative (ESSI) with fourteen other allied countries (twenty-one countries a year later), thus positioning Germany as the leader of a “European pillar” within NATO. France was not involved, as its government, arguing “European sovereignty,” contested the technical and industrial aspects and strategic implications of this initiative. This explains the postponement of the Franco-German Council of Ministers meeting on October 26, 2022. This “sky shield” would combine the Israeli Arrow 3 for high-altitude missile interception, the American Patriot, and the German Iris-T for lower altitudes. At first glance, France and Italy, manufacturers of the Mamba (SAMP/T) system, would therefore not be involved, nor would Poland, which prefers to acquire its anti-aircraft and anti-missile systems at a national level (it already has Patriots). On October 13, 2022, the defense ministers of the countries participating in the initiative signed a letter of intent and a ceremony was held at NATO headquarters. The aim was to jointly purchase air defense and anti-missile systems to be deployed within the NATO framework in order to counter conventional Russian ballistic threats (which is not the objective of NATO’s missile defense). France criticized the project for technical and industrial reasons, but also for strategic ones: it insisted on the virtues of nuclear deterrence and therefore on maintaining the balance between nuclear weapons, deep strike capabilities, and missile defense. However, the issue was not closed. At the Franco-German Ministerial Council on January 22, 2023, an opening was glimpsed. In Munich on February 17, 2023, Emmanuel Macron called for a “conference on European air defense” to “address this issue from an industrial perspective, with the participation of all European manufacturers who have solutions to offer, but also from a strategic perspective and, I would say, perhaps primarily from a strategic perspective, including the issue of deterrence .” Since then, the positions of the various parties have hardly changed. The fact remains that the war in Ukraine, as well as other armed conflicts, around Nagorno-Karabakh and in the confrontation between Israel and Iran, remind us of the need for comprehensive air and missile defense, i.e., a multi-layered defense against multiple threats from the sky, ranging from drones (killer drones and kamikaze drones) to ballistic missiles and hypersonic weapons.

Jean-Sylvestre Mongrenier

Associate professor of history and geography and researcher at the French Institute of Geopolitics (University of Paris VIII). Author of several books, he works within the Thomas More Institute on geopolitical and defense issues in Europe. His research areas cover the Baltic-Black Sea region, post-Soviet Eurasia, and the Mediterranean.

1. In a way, the discussions between the United States and its European allies at the time foreshadowed the debate, which has been ongoing since the 1970s, on “burden sharing” in common defense.
2. The United States and Russia withdrew from this treaty in 2019. Experts on these issues believe that Moscow was indeed violating the treaty. The missile incriminated by the Americans and their allies is the “Novator 9M729″ (the SCC-8 in NATO nomenclature), with a range well over 500 kilometers. In truth, this problem dates back to Barack Obama’s first term in office. In 2010, the deployment of the Iskander weapons system in the Kaliningrad enclave (formerly Königsberg), with a range exceeding 500 kilometers, was already raising questions. The issue was officially broached in 2013, but the Russians did not respond. It escalated with the deployment of the SCC-8 (an improvement on the Iskander system) in 2016, near the Caspian Sea and east of the Ural Mountains. This Russian violation is a deliberate decision that constitutes revenge for the 1987 treaty, which was poorly received by the Soviet military nomenklatura and the “security organs” (KGB and others) from which the Russian ruling class originated, right up to the highest levels of power: the INF Treaty is associated with the end of the USSR, the retreat to the borders of 17th-century Russia, and also to the near-bankruptcy of the military-industrial complex during the 1990s.
3. It is true that Donald Trump’s latest statements on the need to resume U.S. nuclear testing invite us to qualify the thesis of an almost congenital aversion. It should be noted, however, that the U.S. Department of Energy specifies that the tests would not involve nuclear warheads but the delivery systems designed to carry them.
4. cf. Emmanuelle Maître, “B61-12 – Operational deployment in Europe confirmed?”, Observatoire de la dissuasion, FRS, February 2025
5. See the Northwood Declaration of July 10, 2025, signed by French President Emmanuel Macron and British Prime Minister Keir Starmer. This declaration commits Paris and London to coordinating, without merging, the nuclear forces of both nations; it reiterates that “no extreme threat to Europe would leave Paris or London indifferent.”
6. This option assumes that the United States will agree to modify the F-35 so that it can carry French nuclear weapons, or that Germany and Poland will acquire Rafale aircraft. It is therefore more likely that France’s European allies will simply provide the logistics needed to deploy the French air strike force.
7. France does not participate in NATO’s GPN work, but it cooperates with the United States and the United Kingdom in a trilateral framework. On this issue, see Jeffrey Lewis and Bruno Tertrais, “Dissuader à trois : la coopération nucléaire entre les États-Unis, la Grande-Bretagne et la France” (Tripartite deterrence: nuclear cooperation between the United States, Great Britain, and France), Revue Défense Nationale, 2016/, no. 788.
8. See below (Addendum).