LSE Fellows Dr Jacklyn Majnemer and Dr Patrick Gill-Tiney explore the dilemmas around European nuclear deterrence since Trump’s election.

Would the United States risk nuclear war with Russia to protect its allies? This question has returned with a vengeance given President Trump’s wavering support for NATO and the now well-documented anti-European sentiments expressed by high-ranking officials. In response, several NATO allies have publicly voiced concerns and sought new assurances.

This blog post briefly reviews the options: (1) do nothing, (2) receive a new and deeper US commitment, (3) develop an independent nuclear capability, (4) increase investment in conventional capabilities, and (5) seek nuclear assurance from the UK and/or France. These options are not mutually exclusive: for example, European allies could pursue both substantial conventional arms investment and develop an intra-European extended deterrent arrangement as an alternative to American extended deterrence. So far, European states have taken the most concrete steps towards increasing their conventional capabilities. 

Do Nothing or Renewed US Commitment

These options are superficially distinct, but in practice very similar. Neither address the underlying security concerns of these states. A renewed US commitment could, for example, take the form of new American nuclear weapons deployments within Europe. These actions could signal increased American willingness to use nuclear weapons to defend European allies.

However, these moves also risk exacerbating tensions with Russia, which would view any augmentation of NATO’s nuclear sharing posture as a hostile move. Given the NATO-scepticism that pervades the White House, this move seems unlikely and of course, could be withdrawn. Increasing American nuclear deployments to Europe does not fix the underlying issue of American unreliability: whether the US would really follow through on its commitments and use these weapons to defend Europe if Russia attacked.  

Go Nuclear

European allies could also pursue their own nuclear arsenals. This option would provide sovereign control over nuclear use and address the issue of will: there would be less doubt that a state would use nuclear weapons to protect its own security rather than that of an ally. However, there are significant practical obstacles to build the capabilities needed for a credible nuclear deterrence.

Developing the weapons, delivery systems, and infrastructure necessary for a nuclear arsenal that could survive a first strike would require significant time and resources. The length of time needed to achieve these capabilities creates a window of vulnerability that could invite a preventative attack – the very thing that these states want to avoid. In addition to these technical and security challenges, any such pursuit would violate the Nuclear Non-Proliferation Treaty (NPT), to which all European allies are parties, incurring major reputational costs and economic costs if states impose sanctions to counter nuclear pursuit.  

Conventional Buildup

European allies could also invest more heavily in conventional weapons, equipment, and personnel. Increased conventional capabilities and forces make it less likely that a Russian attack would be able to advance and hold territory, which makes an offensive in Europe a less attractive option. This is what is known as deterrence by denial: when an adversary is dissuaded from attacking because they know their military campaign will not succeed. As European doubts about American reliability extend to whether they will provide conventional support in the face of a Russian attack, European allies are concerned with their reliance on US conventional forces and capabilities, as well as American companies that produce conventional weapons and equipment.  

European allies have taken concrete steps to shore up their conventional defences. For example, Poland has significantly increased defence spending, and Germany is set to follow suit. The EU has recently approved a €150 billion defence fund as part of their Security Action for Europe (SAFE) programme, aimed at increasing defence spending and investment in European defence industries. However, questions remain about whether current investment plans are sufficient and can be implemented quickly enough to build up a credible conventional defence to a Russian attack. 

A European Nuclear Umbrella

The UK and France could also step in to replace the US as the main nuclear guarantor in Europe. Given their location and integration with Europe, both the UK and France should be more likely to view an attack in Europe as directly undermining their vital security interests than the United States. However, several issues affect the credibility of an intra-European nuclear umbrella. 

While the UK’s nuclear force is operationally independent of the US, it is heavily reliant on the US for its nuclear infrastructure, particularly the Trident missiles needed to deliver its nuclear warheads. The UK does not currently have the domestic capacity to produce or service its missiles, and they need to return to the US for maintenance every few years.

France produces all elements of its nuclear arsenal domestically and therefore does not face the same risks related to dependency on the US. France’s deterrent incorporates both air and submarine launched missiles. However, despite rejoining NATO’s integrated military command in 2009, France still maintains its independence from NATO on nuclear matters. It has never participated in NATO’s Nuclear Planning Group (NPG), the alliance’s forum for nuclear coordination and strategy. While Macron has voiced support for providing extended deterrence commitments to Europe, there is a strong possibility that the next President of France will be more sceptical of NATO, friendly towards Russia, and unwilling to provide a nuclear umbrella. 

Some commentators have noted the stark difference in the number of nuclear weapons between the US and European nuclear powers. As Table 1 below shows, while the US’s stockpile totals about 3,700 warheads, including warheads that are deployed and those that are in storage, France has about 290 and the UK about 225. However, many experts agree that European nuclear powers do not need to try to mirror the US’s nuclear stockpile or dramatically increase their total numbers of warheads.

However, some have argued that some increases in the number and types of nuclear weapons available to France and UK would be necessary to build a credible extended deterrent. Many experts have emphasised that a European nuclear deterrent would not replace the need for greater investment in conventional forces and arms. An effective European extended deterrence arrangement would therefore require both nuclear and conventional dimensions. 

Technically, both the UK and France have already implicated themselves in the nuclear defence of European allies: the UK through its nuclear participation in NATO (reaffirmed and explicitly referred to in the newly published Strategic Defence Review) and France by declaring its vital interests to have a ‘European dimension’. However, their policy related to the defence of European allies could be clearer and explicitly designed to operate independent of the United States. Some commentators have suggested more robust intra-European arrangements for nuclear consultation, information-sharing, and planning to strengthen reassurance and coordination; however, these might be difficult to negotiate. Non-nuclear European allies would need to be reassured that they will be both defended and consulted, without undercutting the UK and France’s sovereign authority over decisions on nuclear use. 

Conclusion

The future of European nuclear deterrence is in flux. Non-nuclear allies face a problem in which all solutions are suboptimal. Thus far, while there has been increased discussion about various nuclear options, European countries have taken more concrete steps towards shoring up their conventional capabilities.  

Featured image generated by Patrick Gill-Tiney using ChatGPT.