Europe Needs More Conventional Forces, Not Its Own Nukes

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All eyes will be on Milwaukee, Wisconsin on July 15 when presidential candidate Donald Trump takes to the stage at the 2024 Republican National Convention. Just four days earlier, President Joe Biden will address NATO’s 75th anniversary homecoming summit in Washington. Across the Atlantic, leaders in Europe and Moscow will be listening closely to both of them.

European leaders will be nervous. They are already on edge after Trump’s previous comments about NATO at a rally in South Carolina earlier this year. In February he encouraged Russia to “do whatever the hell they want” to allies that do not spend more on defense. This caused widespread alarm about the reliability of U.S. security guarantees under a second Trump administration.

These concerns were enough to bring dormant “zombie debates” over whether Europe should pursue an autonomous nuclear deterrent back to life. As Christian Lindner, Germany’s finance minister and the leader of the Free Democratic party, said: “We should understand Donald Trump’s recent statements as a call to further rethink this element of European security under the [nuclear] umbrella of NATO” (authors’ translation). Similar comments were also made by other prominent politicians in Germany, Poland, and the European Parliament.

However, these debates are a red herring. Europe cannot afford a new nuclear deterrent, nor does it need one. U.S. extended nuclear deterrence is more resilient than it seems, while Europe already has two major powers with nuclear weapons. Such debates only serve to distract from the real issue in European defense: a lack of combat power, which undermines conventional deterrence. When they meet at the Washington summit on July 10–11, NATO leaders should focus on boosting Europe’s own conventional, not nuclear, forces.

New Wine in Old Bottles

Debates about developing a national or collective European nuclear deterrent have a long history. Despite initial opposition by the Kennedy administration, Britain and France’s Cold War nuclear programs were developed to both supplement the U.S. nuclear umbrella (in London) and provide some redundancy against it (in Paris). Various abandoned attempts to establish a European bomb during the Cold War include an attempted agreement in the margins of the 1957 “Euratom” treaty (to develop nuclear energy in Europe), failed efforts by European NATO allies to develop a nuclear “Multilateral Force” (the idea was later referred to as the “multilateral farce”), and the “European clause” to the 1968 Non-Proliferation Treaty (NPT). In the 1990s some argued for the fledgling European Union to develop a nuclear program, but these calls soon disappeared along with the Soviet threat.

These debates have now gained traction again due to Russia’s invasion and nuclear posturing. Political voices in Germany are leading the debate, including Manfred Weber, a prominent leader in the European Parliament, and Finance Minister Christian Linder. Polish officials have also made similar points. Yet several senior voices urge more caution. German chancellor Olaf Scholz suggests that “Germany does not need its own nuclear weapons . . . There is no reason to question NATO and transatlantic cooperation now” (authors’ translation). Meanwhile, his defense minister, Boris Pistorius, warned against “starting such a discussion with such carelessness just because Donald Trump, who is not even a presidential candidate, makes such statements.” NATO secretary general Jens Stoltenberg thinks the debate is “not helpful.” They all argue that the best solution is the status quo: continuing to support collective nuclear deterrence through NATO.

Although the concerns of some European leaders are driven by U.S. political uncertainty, they also transcend Trump. The U.S. rebalance toward the Indo-Pacific—and away from Europe—plus the emerging demands of “two-peer” deterrence pose structural challenges that will endure no matter who occupies the White House. Some proponents advocate an independent European deterrent to boost autonomy as an end in itself.

Either way, the technical obstacles, political hurdles, and economic costs to establishing an independent European deterrent would be prohibitive. The practical challenges of developing and operating a collective deterrent outside of NATO would be formidable. Three EU member states are now party to the 2017 Treaty on the Prohibition of Nuclear Weapons (TPNW): Austria, Ireland, and Malta. As Scholz put it: “there will not be any ‘EU nuclear weapons’—that is simply unrealistic.” Meanwhile, the pursuit of a German deterrent would have high costs, violate the NPT, and go against public opinion. Polling suggests that any such move is unlikely to be met with broad support, given that Germany has consistently opposed nuclear weapons in the past and now abstains from nuclear power (which was phased out last year).

The most viable path to an autonomous European bomb might be to “Europeanize” the French deterrent. President Macron implied this in 2020—when he called for a strategic dialogue in Europe “on the role played by France’s nuclear deterrence in our collective security”—and reiterated the offer again recently. The offer was welcomed by Scholz, while a 2017 review by German lawmakers assessed that nuclear sharing with France—bilaterally or through the European Union—would be legal. However, this would violate the commitment by some EU member states to the TPNW. Doing so outside of the European Union (and NATO) would require a new institution, adding another layer of complexity—and potential division—to Europe’s security architecture.

Still a Red Herring

All this means that the so-called “Eurobomb,” “Eurodeterrent,” or “Euronukes” debate is—in the words of Bruno Tertrais—still a red herring. A European nuclear deterrent is not only unlikely, it is also unnecessary—for two reasons.

First, the U.S. nuclear umbrella is more robust than Trump’s comments make it seem. In the 1960s the British defense minister Denis Healey said, “it takes only 5% credibility of American retaliation to deter the Russians, but 95% to reassure the Europeans.” Healey’s Theorem, as it became known, is often invoked around the challenges of assuring allies about U.S. extended nuclear deterrence commitments. But it also highlights that deterrence rests on uncertainty, not certainty. As an Estonian analyst explained in the Wall Street Journal: “For Putin, what really matters is that the other side that opposes him has nuclear weapons and is credible about their use in extreme circumstances. As long as there still is this 1% chance of the nuclear element, the deterrence may still hold.”

Despite the former president’s loose language—and even if he took a more cavalier position if he returned to office—the United States’ adversaries can never be certain that he would rule out nuclear use in “extreme circumstances.” Moreover, despite his acerbic rhetoric about NATO allies during his four years in office, President Trump’s policies—such as the 2018 Nuclear Posture Review—amounted to a strengthening, not weakening, of the U.S. nuclear enterprise and extended deterrence. Actions speak louder than words.

The second reason Europe does not need a nuclear deterrent is because it already has two. The United Kingdom and France both extend their nuclear deterrents to Europe. The United Kingdom does so through NATO, officially declaring: “We would consider using our nuclear weapons only in extreme circumstances of self-defence, including the defence of our NATO allies.” While France does not participate in NATO’s nuclear planning or declare its deterrent to NATO, it has made clear that its nuclear arsenal is at the service of European security. As President Macron stated in 2020 (and reiterated in April): “Let’s be clear: France’s vital interests now have a European dimension.” (Macron followed the example of de Gaulle and Pompidou, who made a similar declaration in 1964, and several leaders since.) Moreover, since 1995 France and the United Kingdom have treated their vital interests as concomitant.

The British and French nuclear arsenals are much smaller than that of the United States—consisting of a few hundred warheads rather than a few thousand—but are large enough to inflict unacceptable damage. These two European arsenals enhance the political credibility of NATO’s deterrent by making the perennial question of whether any U.S. president would “trade New York for Paris” less relevant.

Nuclear Burden Sharing

A less fraught option to strengthen nuclear deterrence in Europe might be to enhance NATO’s nuclear sharing and stationing arrangements. These allow nonnuclear allies to participate in NATO’s nuclear mission, demonstrating alliance solidarity and burden sharing. Several allies currently operate dual-capable aircraft that can carry U.S. B-61 nuclear gravity bombs. Although not confirmed by official government sources, it is widely believed that around 100 U.S. warheads are located in five European NATO nations: Belgium, Germany, Italy, the Netherlands, and Turkey.

Since the end of the Cold War the number of U.S. nuclear weapons in Europe has been drastically reduced, while some allies have since withdrawn from nuclear sharing. However, Russia’s war in Ukraine has reignited the debate. For example, Polish president Andrzej Duda recently said “we are ready” to host U.S. nuclear weapons through NATO—even if Prime Minister Donald Tusk was more cautious. Several allies have also procured the dual-capable F-35A aircraft, which has been suggested as another way to strengthen and expand nuclear sharing.

A key concern over expanding nuclear sharing is nonproliferation. All NATO allies are party to the NPT, which restricts the exchange of nuclear materials during peacetime. While some argue that nuclear sharing challenges the NPT, NATO has long viewed these arrangements as compliant. Nuclear sharing predates the NPT, and was conceived with nonproliferation in mind: one of the original goals of the policy to share U.S. nuclear weapons was to remove the incentive for Europeans to develop their own. While the alternative option of “friendly proliferation” has long been advocated by some as a solution to U.S. overstretch, creating more nuclear weapon states would undermine Washington and NATO’s long-term focus on disarmament.

However, doing so might transgress the 1997 NATO-Russia Founding Act. The act noted both parties’ progress on nuclear disarmament and reiterated that NATO allies “have no intention, no plan and no reason to deploy nuclear weapons on the territory of new members.” Many consider it a “dead letter” since Russia invaded Ukraine in 2014. As Stoltenberg declared in 2022: “We see an extremely blatant and flagrant violation of the Founding Act with the invasion of Ukraine.” Even if the act is “hanging by a thread,” NATO has never officially renounced it. The alliance still respects many of its principles, even agreeing in Vilnius to keep its forward defense ground forces below the brigade level, which Russia has long equated to the “substantial combat forces” that both committed not to deploy forward in 1997. However, the act stated that allies “do not foresee any future need” to modify their nuclear posture—Russia’s invasion and heightened nuclear threats toward Europe may have changed that assessment.

Conventional Deterrence Is the Real Problem

If European NATO allies wish to hedge against Russian revanchism and U.S. political uncertainty by bolstering nuclear deterrence, strengthening nuclear sharing offers a better route than the dead-end Eurobomb debate. However, Europe’s most pressing problem is not nuclear but conventional deterrence.

The threat of a conventional armed attack on NATO is higher than at any time since the Cold War. Estonian prime minister Kaja Kallas has said: “It’s a question of when they will start the next war.” Several European leaders have warned that Russia could attack NATO allies “within five years.” Despite Russia’s staggering losses in Ukraine, deputy U.S. secretary of state Kurt Campbell said recently that “Russia has almost completely reconstituted militarily.”

The nature of conventional deterrence means that European allies cannot rely on Healey’s Theorem, which only applies because of the catastrophic potential of nuclear threats. Instead, they must have sufficient capable forces in place and the political will to use them. During the Cold War, NATO allies invested heavily in conventional, forward-based “shield forces” in West Germany and central Europe. These forces boost the credibility of nuclear deterrence by deterring any incursion which could lead up the escalation ladder toward nuclear use.

Yet today, Europe’s conventional forces are underpowered. Even though European defense spending has risen by a third over the last decade to approximately $380 billion, years of reductions after the Cold War left European allies unable to conduct high-end combat missions alone, without U.S. support. While allies agreed to strengthen collective defense at the 2022 Madrid summit, many of them lack sufficient personnel, equipment (much of which has gone to help Ukraine), and industrial capacity—especially compared to Russia, which is now on a war footing. This situation led the foreign ministers of France, Germany, and Poland to urge Europe to take more responsibility for its defense, while President Macron has warned that Europe is in “mortal” danger.

Fixing this problem will require European NATO leaders to agree to four “mores”: more cash, more combat power, more capabilities, and more cooperation. More cash means continued increases in European defense spending beyond the 2 percent of GDP target set by NATO allies a decade ago. More combat power means converting this spending into military outputs more efficiently: since 2014, the number of combat battalions, main battle tanks, armored vehicles, and artillery has remained static or fallen across most European armies. More capabilities means filling the known gaps in Europe’s critical capabilities, such as air and missile defense, long-range fires, air transport, military mobility, cyber, and space. More cooperation means reversing the decline in military and industrial collaboration, which makes European defense more fragmented and expensive.

Back to Basics in Washington

When allied leaders gather in Washington for NATO’s 75th anniversary summit in three weeks, their first task will be to strengthen deterrence and defense. The main focus of these efforts should be on Europe. However, European allies should not make the mistake of pouring limited political energy and resources into an independent nuclear deterrent, which remains unnecessary and a red herring. If European leaders want to strengthen nuclear deterrence, they could consider expanding existing nuclear sharing arrangements through NATO or taking up President Macron’s offer to discuss supporting France’s nuclear enterprise. However, the main task ahead for Europe is the same as it was during the Cold War: strengthen conventional deterrence.

For its part, the Biden administration should take the opportunity in Washington to boost the credibility of its extended deterrence in Europe. It should do this by restating its commitment to NATO’s Article 5 and its position that any use of nuclear weapons by the Kremlin will be met with catastrophic consequences for Russia. This would strengthen deterrence while reassuring the United States’ European allies that they do not need to go their own way. It would be even better if candidate Trump said the same thing four days later in Milwaukee.

Doreen Horschig is an associate fellow with the Project on Nuclear Issues at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Sean Monaghan is a visiting fellow in the Europe, Russia, and Eurasia Program at CSIS.

Sean Monaghan
Visiting Fellow, Europe, Russia and Eurasia Program