The Trump administration’s hostile rhetoric towards Europe, including remarks about potentially withdrawing or relocating US troops stationed there, has reignited debates about Europe’s nuclear deterrence.
Europeans are worried that the US might even go as far as withdrawing the nuclear weapons stationed there as part of its extended deterrence agreement with NATO.
That guarantee dates back to 1949 and includes US nuclear weapons kept on European territory. It is important to note that, despite its insistence on Europeans providing their own security, the US has not so far suggested withdrawing US nuclear weapons from Europe, or made any practical moves to signal this.
An important component of a strong deterrence posture is resolve – the willingness to follow through if there is a threat. What the recent rhetoric has suggested is that the US might lack resolve to support Europe in a crisis, therefore weakening European deterrence.
Matching US forward-deployed nuclear weapons is not feasible
A few options have been mooted to replace US extended deterrence with something less dependent on Washington. French president Emmanuel Macron has suggested several times in the past that France could extend its nuclear umbrella to protect other European states.
This would mean establishing formal agreements in which French and British nuclear forces explicitly commit to deterring threats against NATO allies, involving joint decision-making structures and nuclear sharing arrangements. Friedrich Merz, Germany’s incoming chancellor, proposed that France and the UK together could provide extended deterrence guarantees to Europe.
The devil is in the details of such ideas. France and the UK have different nuclear arsenals to the US (in terms of types of launch platforms and vast differences in size), making it impossible to replace US weapons in Europe with French or British ones. France has air-launched and submarine-launched while the UK only has submarine-launched nuclear weapons.
Although technically independent from the US and only launched at the prime minister’s decision, UK nuclear weapons are heavily reliant on US technology. The UK designs and produces its own warheads, but it buys the aeroshells for the warheads and the Trident missiles used as delivery vehicles from the US.
Periodically these missiles have to be serviced in the US. Should the US decide to stop supplying or servicing the missiles, the UK would need to replace them before they expire. This would not be an easy task: all components of the nuclear capability are produced for each other – a new missile would need to be able to carry the warheads, and fit in an existing submarine launch tube.
Even though the UK has fewer nuclear weapons than France, it already provides an extended deterrence guarantee to other NATO members by being a member of the NATO Nuclear Planning Group (NPG) and having designated its nuclear weapons to protect Europe.
By contrast, fellow NATO member France has always reserved its nuclear weapons for national protection. Its nuclear enterprise is also completely independent from the US, producing all components required domestically.
If France wanted to signal its commitment to extending nuclear deterrence to Europe, the simplest step would be to change its nuclear posture to explicitly include Europe – something French officials claim has been the case since the 1970s anyway – and to join the NPG.
Relocating French nuclear forces to other countries would miss the point
One suggestion for strengthening European deterrence has been that France could deploy its nuclear-capable Rafale aircraft to Germany or other NATO states.
But, as France neighbours three of the countries currently hosting US nuclear weapons (Germany, Belgium and the Netherlands), this would provide only marginal improvements. The challenge is not where the aircraft are based but rather how they are integrated into NATO’s command and planning structures.
Simply moving the aircraft does not solve the problem of strategic coordination and decision-making in a crisis. If France were to join the NPG, French and NATO nuclear policies would be better aligned, allowing the French nuclear capabilities to augment a European deterrence posture, alongside the UK. This would break with a decades-long tradition of French nuclear independence in which nuclear weapons were a clear symbol of France’s sovereignty as a nation.
Joining the NPG would not have to entail devolving launch decisions to allies. Both US and UK nuclear decision-making remains completely sovereign. But it would mean that French nuclear forces are integrated into NATO nuclear exercises so that allies can practise working together in a crisis.
Developing nuclear weapons in European countries would be destabilizing
Late last week, Poland’s prime minister Donald Tusk also raised alarm across the continent by saying that Poland must consider acquiring nuclear weapons to address US threats to stop protecting European allies.
This would be a highly risky and impractical solution. Developing an independent nuclear capability for Poland – or any other non-nuclear European country – would significantly destabilize the region.
A European state pursuing nuclear weapons would violate and threaten the credibility of the nuclear Non-Proliferation Treaty (NPT) and would risk other countries following suit, prompting a dangerous arms race.
Breaking the NPT and proliferating would erode the broader international arms control architecture and potentially weaken other critical treaties and norms, such as those governing chemical and biological weapons.
Rather than enhancing deterrence and security, proliferation in Europe would undermine global non-proliferation efforts and increase the risk of regional instability, miscalculation and misunderstanding at a time when tensions are already high.