Europe thinks the unthinkable on a nuclear bomb
“WE WOULD BE safer if we had our own nuclear arsenal,” Donald Tusk, Poland’s prime minister, told his country’s parliament on March 7th. The reason he gave was the “profound change of American geopolitics”, a euphemism for Donald Trump’s diplomatic arson, which also required Poland to expand its conventional armed forces.
Mr Tusk was not proposing a Polish nuclear bomb—at least not immediately: “The road to that would be very long and there would have to be a consensus.” Instead, he was responding to a call by Friedrich Merz, Germany’s incoming chancellor, for talks with Britain and France on “supplementing the American nuclear shield”. On March 5th Emmanuel Macron, France’s president, announced a “strategic debate on using our deterrence to protect our allies on the European continent”.
That debate will need to confront two problems: credibility and capability. For nearly 80 years America has held a nuclear umbrella over Europe. Yet extended deterrence is a strange and unnatural thing. One country must promise to use its nuclear forces—and thereby risk nuclear annihilation—on behalf of another. The difficulty of making that promise credible is what drove America to build a huge arsenal and to scatter it across the world. Britain’s nuclear forces, though modest, are also “assigned” to the defence of NATO. Though only the prime minister can authorise their use, the implicit promise is that they would be used to defend allies such as Finland, Romania or Turkey.
France has a more complicated relationship to extended deterrence. It pursued an independent nuclear deterrent in the 1950s precisely because it believed, to a greater extent than Britain, that America’s umbrella was not dependable. France did not join and still does not take part in the Nuclear Planning Group (NPG), a NATO forum in which 31 allies discuss nuclear policy. “The idea is really to keep options open for the president,” explains Emmanuelle Maitre of the Foundation for Strategic Research in Paris. “There is a kind of reluctance to commit…to anything that could limit [his] freedom of action.”
Yet France’s leaders have also said its vital interests have a “European dimension”. In 1995 Britain and France agreed that “the vital interests of one could not be threatened without the vital interests of the other equally being at risk”—an implicit expansion of the horizon of French deterrence. The same language was used in the Franco-German Aachen treaty 24 years later. Even Jordan Bardella, the leader of the far-right National Rally party, recently acknowledged that French nuclear weapons “protect, by definition, certain neighbours and certain European partners”.
The question is what this means in practice. In 2022 Mr Macron said he would “evidently” not respond in kind if Russia used nuclear weapons in Ukraine. French vital interests were “clearly defined”, he claimed, confusingly, and “these would not be at stake if there was a nuclear ballistic attack in Ukraine”—or, he added, unwisely, “in the region”. That phrase seemed to exclude eastern European EU and NATO allies from protection. Since then Mr Macron has taken a hawkish turn, successfully rebuilding ties to eastern European states. But even France’s closest allies have private doubts as to whether successive presidents in the future will be willing to risk nuclear war to support them.
European allies are now asking how far Mr Macron might be prepared to go. “I would like to know, first of all, in detail what it means in terms of power to use these weapons,” Mr Tusk told journalists, seeming to hint at a model in which Poland would be vested with some launch authority. “If we were to decide on this, it would be worth making sure it is in our hands and we make the ultimate decisions.”
La bombe, c’est la mienne
That carries echoes of the proposed Multilateral Nuclear Force, a 1950s concept for a jointly owned and operated pan-European nuclear force. The idea was that 25 ships would each carry eight Polaris missiles, with the crew of each one drawn from at least three NATO countries. Later, in the 1960s, Britain proposed an Atlantic Nuclear Force that would put British and American nuclear forces under international command, with national vetoes.
Those plans largely fizzled and are unlikely to find favour today. Mr Macron appears to have ruled out any movement towards joint launch authority. France’s nuclear deterrent is “sovereign and French from start to finish”, he insisted. The decision to use nuclear weapons “has always been, and will always be, up to the president and commander-in-chief of France”. There are legal obstacles, too. If Britain or France were to transfer custody and control of their own nuclear weapons, or if non-nuclear states were to build new ones, they would have to leave the Nuclear Non-Proliferation Treaty—or violate it.
There are other options, though. Peter Watkins, a former British defence official who oversaw nuclear policy, proposes that France could join NATO’s NPG as an observer rather than participant. A punchier option would be for France to publicly clarify the European dimension of its interests. Bruno Tertrais, a French nuclear expert, has suggested that France could simply make it clear that Article 42.7 of the Lisbon Treaty, the EU’s mutual-defence clause, “could be exercised by any means, thus including nuclear weapons”.
Another course would be to borrow from America’s approach to extended deterrence. The United States has long stationed 180 or so B61 tactical nuclear bombs in Europe. They remain under American control. But the air forces of Belgium, Germany, Greece, Italy, the Netherlands and Turkey practise carrying and delivering them using dual-capable aircraft. Other air forces contribute conventionally armed aircraft to support those missions, performing tasks such as jamming enemy radars and refuelling (see map).
Britain would find it tricky to mimic those nuclear-sharing arrangements. Since the 1990s all its nukes have been on submarines whose whereabouts remain secret. Subs can be used for signalling—in early 2022, soon after Russia’s invasion of Ukraine, France took the unusual step of putting three of its four nuclear-armed boats to sea—but you cannot sail one up the Rhine or Vistula to reassure allies.
Planes are a different matter. France possesses air-launched nuclear weapons to send a “final warning” to an enemy, before it fires submarine-launched missiles at, presumably, Russian cities. In its Poker exercise, the French air force practises long-range nuclear bombing raids four times a year. In 2020, after the shock of Mr Trump’s first term, Mr Macron invited allies to “associate” with French nuclear drills. Voilà, in 2022 an Italian tanker refuelled French aircraft in one such exercise. In recent days, other allies have offered to take part, says a person familiar with those talks.
The question is how much further this might go. French nuclear-capable aircraft increasingly take part in conventional exercises abroad, including with Lithuania and Germany last year. In 2018 Mr Tertrais suggested that France could eventually rotate unarmed nuclear-capable Rafale fighter bombers to eastern European air bases “to demonstrate its solidarity”. That would not just be a political signal. It would also extend the range at which France could strike Russia and safely return its aircraft. In more extreme scenarios, Mr Tertrais writes, France could base tens of air-launched missiles in Germany, allow these to be carried by allied jets or even convene “a European nuclear maritime task-force”.
The problem with all this is scale. America’s arsenal is large enough, notes Mr Watkins, “that it is plausible that it could employ some weapons in response to [an] attack on an ally while still having plenty in reserve…to deter an attack on the US homeland.” In Britain’s case, he adds, using a single missile at lower levels of escalation—say, in response to Russia’s use of a tactical nuclear weapon—“could compromise the location of the sole deployed submarine”. These problems are hardly insurmountable. Britain raised its cap on warheads in 2021 and could do so again. Moreover, if it built five rather than four Dreadnought-class submarines, the first of which is expected in the early 2030s, it could put two boats out to sea at once.
Assuming, that is, it could build more. The very threat which necessitates these schemes—Mr Trump’s hostile attitude towards allies—might also complicate the response. Britain depends intimately on America for the design, manufacture and maintenance of nuclear weapons. The Trident missiles that carry them are leased and held in America. Their British warheads must fit inside an American “aeroshell”. And the tubes which hold the missiles in the Dreadnought class are the same as those in America’s Columbia-class subs.
A new entente cordiale
In the worst-case (which few officials think is likely), if America were to cut off support, Britain could hang on to the missiles in its possession, probably for some years. But its future warhead and submarine plans would no longer be viable. One option for Britain would be to revive the idea of co-operation with France. In the 1970s France proposed selling submarine-launched missiles to Britain and, in the 1980s, suggested co-developing a nuclear-capable cruise missile.
That would be a dramatic step. Mr Macron’s “strategic debate” is at an early stage. For now, says Héloïse Fayet of the IFRI think-tank in Paris, “there are no talks about putting French nuclear weapons outside French territory”, let alone diluting French authority to use them. “The idea is more to advance on the political side,” says Ms Fayet, “trying to find, at a very high level, shared vital interests between, for example, France and Sweden, or France and Germany”, as well as expanding allied involvement in French nuclear exercises. “There are plenty of ideas, but we are lacking French political guidance.” That might disappoint the likes of Mr Tusk, who see a crisis brewing. Even so, Mr Trump has sparked Europe’s most profound nuclear debate since the 1950s. ■