Can Europe build a credible nuclear deterrent without US support?

Between US President Donald Trump’s long-held scepticism of NATO and his administration’s increasingly close alignment with the Kremlin, the US is suddenly a weaker security guarantor for Europe than at any time since the end of World War II.

And given that Russian President Vladimir Putin has repeatedly threatened the use of nuclear weapons since he launched the full-scale invasion of Ukraine, the prospect of Washington abdicating its security role has massive implications for Europe’s ability to deter a nuclear strike.

Marion Messmer, a senior research fellow in the International Security Programme at UK think tank Chatham House, told Euronews that one of the first challenges for Europe will be to find a way of making its nuclear deterrent appear credible without US involvement.

“One of the challenges in constituting a European nuclear deterrence capability is Russian perception,” she explained. “Russia sees the United States as the main driving force behind Europe, and will invariably take a European-only deterrence capability less seriously.”

“One way around that is by demonstrating joint force, such as through a UK-French offer, even if it is numerically different from a US offer," Messmer said.

She also pointed out a key difference between the two European nuclear powers’ current setup, one that may need to be addressed depending on what path forward Europe decides to take.

“French nuclear doctrine currently reserves French nuclear weapons for national use only. Presumably, a European role for French nuclear weapons would therefore require a change in nuclear doctrine," Messmer explained.

"The UK’s nuclear weapons are already part of NATO’s nuclear deterrence capability, so it would depend on the UK’s exact role in this joint venture whether any policy changes would be required.”

But before the actual setup of any new formal agreement, there are major issues that need to be addressed by the nuclear powers themselves.

A sinking feeling

Compared to the major nuclear-armed states, the UK deploys only a small deterrent. At any given time, one of the country’s four nuclear-capable Vanguard submarines is on patrol armed with US-made Trident II D5 long-range ballistic missiles.

The patrolling submarine carries with it a so-called “Letter of Last Resort”, a note signed by the prime minister with instructions to the crew on what to do if the UK is hit with a nuclear strike.

Among the options that can be given are a retaliatory strike, non-action, or for the submarine to offer itself to an ally.

MPs voted to maintain and overhaul Trident in 2016, but it suffers many logistical complications. Most notably, while its warheads are manufactured domestically, the missiles it uses are held and maintained in the US, specifically at Kings Bay Submarine Base in Georgia.

The future of the programme is also under a cloud thanks to a series of hardware problems.

The last two test firings of Trident missiles from Royal Navy submarines, in 2016 and 2024, both failed; the latter incident occurred while the then-defence secretary was aboard the submarine involved, which had just been refitted at huge expense over the course of seven years. 

Trident is also extremely politically sensitive. British anti-nuclear weapons activism has a long history, reaching its zenith in the 1980s when US cruise missiles were deployed at RAF airbases on the British mainland. They were ultimately removed as the Cold War came to a close.

Today, the British deterrent is built and maintained at a Scottish naval base, HMNB Clyde, only 40 kilometres away from the city of Glasgow. This is a strategic location that allows its submarines access to the North Atlantic — but the Scottish National Party (SNP), which leads the Scottish government and advocates for the full separation of Scotland from the UK, has long opposed the presence of nuclear weapons there, decrying them as immoral and pointing to them as an example of the UK-wide government imposing its will on Scottish voters.

However, since Russia’s full-scale invasion of Ukraine, the SNP has struggled to explain how an independent Scotland could enjoy the protections of NATO, which is at its core a nuclear alliance, while rejecting the use of nuclear weapons altogether.

Lancez la bombe

Europe’s other nuclear-armed power, France, has a very different programme. The Force de Dissuasion (deterrence force) is thought to hold almost twice as many warheads as Trident, and along with a submarine-based capability, the French military also maintains air-launched nuclear-capable cruise missiles which can be carried aboard domestically manufactured Rafale fighter jets.

More crucially in the current situation, the French deterrent enjoys far more independence than Trident, which is heavily entangled in the US defence superstructure and supply chains.

Emmanuelle Maitre, a senior research fellow at the Paris-based Foundation for Strategic Research, told Euronews that as far as the French government is concerned, the Trump administration’s abrupt repositioning vindicates years of argument in favour of European security, with the French deterrent playing a key role.

“At the nuclear level, the French have for long indicated that their nuclear deterrence could be an element of security for Europe at large, because of the ‘European dimension of French vital interests’,” she said.

“What has changed is the more public engagement of European partners on the role France’s nuclear arsenal can play in the defence of the continent.”

This does not, however, imply that a new security arrangement would demand that France dramatically expand its nuclear capability, which remains a fraction of the size of the US and Russian programmes.

“Recognising the European dimension of the French deterrent does not require adaptations,” Maitre said. “France has neither the will nor the capacity to substitute itself for the US, or to adopt a strategy that would require a larger arsenal.”

“In the foreseeable future, its arsenal will be realistically sized to ensure damage to any attack that would threaten its vital interests, but will not be forward-deployed in any other allied countries," Maitre concluded.

Ultimately, it remains to be seen what security arrangement Europe’s major military powers will sign up to. But as things stand, several of the continent’s non-nuclear NATO countries already play a role in nuclear deterrence.

Germany, for instance, may not have a deterrent of its own, but it hosts US-made nuclear weapons at at least one of its bases, and its air force includes planes that can carry them.

Poland, meanwhile, has said it is ready to accept the deployment of NATO missiles on its territory, a development that would put nuclear weapons on its soil for the first time since the end of the Cold War.

Whether or not the heavily US-reliant UK programme and the larger French force can together substitute for a full-blown NATO deterrent, both may have to change dramatically if they are to do so.

But with China expanding its arsenal as Russia still makes sporadic nuclear threats against opponents of its actions against Ukraine, Europe has little time to waste.

As Macron put it in a speech last year, 12 months almost to the day before Trump returned to power: "All the treaties were decided by former USSR and USA. Everything which covered our territory was decided by the big guys in the room, not by the Europeans themselves...When it is about designing our architecture of security, we have to be the one to decide."