UK may ‘step into the breach’ and shield EU ally from Russia as US commitment weakens

The UK’s nuclear umbrella can be extended across Europe, offering a critical deterrence against Russian aggression, according to experts – although there are nevertheless significant hurdles to doing so. With the United States wavering in its commitment to European security under President , the UK has been tipped to step in to fill the void left by Washington, along with France.

Jennifer Kavanagh, Senior Fellow & Director of Military Analysis at the US-based Defense Priorities think tank, said that the UK is well-positioned to play a pivotal role in Europe’s nuclear deterrence. She added: “The UK has the capability and political will to extend its nuclear protection beyond its own borders. In the wake of US hesitations, the UK could step into the breach, ensuring Germany is shielded from Russian nuclear coercion.” Ms Kavanagh, speaking before Friday’s between Mr Trump and Ukrainian President , emphasised the strategic importance of the UK’s nuclear submarines and air force.

She explained: “The UK’s arsenal of nuclear weapons, particularly submarine-launched ballistic missiles, allows for the credible threat of retaliation if Germany were to be threatened by .”

However, such a shift would require significant investment in conventional capabilities as well as nuclear escalation options to ensure the commitment remains credible, she stressed.

She concluded: “Europe cannot afford to rely on the US alone for its nuclear security. But it will require strong leadership, coordination, and investment in both nuclear and conventional capabilities to ensure Europe’s long-term deterrence remains credible.”

Paul van Hooft, an expert on NATO and wider European security arrangements at RAND Europe, also highlighted the complexities of extending nuclear deterrence from France and the UK.

He said: “France is offering the placement of Rafale aircraft that are dual-capable. This does not mean that they always carry nuclear weapons, or that France would base nuclear weapons in Germany. France believes that because they could carry nuclear weapons is significant. They have also said this about the role of these aircraft in the Baltic Air Policing mission. So, this is not the same as what the US is currently doing with the European nuclear sharing states.

“It’s not so much a question of technical feasibility. The US extended deterrence guarantees are primarily political, backed by a large and diverse nuclear arsenal. But for France and the UK to extend deterrence, the primary difficulty would be making that commitment politically credible.”

Mr Van Hooft further explained that the lack of flexible non-strategic nuclear weapons in both the French and UK arsenals could limit their ability to effectively manage escalation in the face of Russian nuclear coercion.

He explained: “Neither of them has the flexible arsenal with non-strategic nuclear weapons with which they can manage escalation.

“France has a non-strategic ‘warning shot’ carried by its dual-capable aircraft. The UK could launch a non-strategic warning from its submarines, but that would probably not be an effective signal.”

Despite these challenges, Kavanagh emphasised that Europe cannot afford to rely solely on the US for its nuclear deterrence. She concluded: “If the UK and France can ensure that their nuclear umbrella remains credible, it would enhance Europe’s long-term security and diminish its dependency on the US.

“But this shift would require significant investment in conventional capabilities as well as nuclear escalation options.”

Mr Van Hooft also noted that while France and the UK could extend their deterrence capabilities, the real difficulty lies in making such a commitment politically credible.

He said: “It’s not so much a question of technical feasibility. For France and the UK to extend deterrence, the primary challenge would be making that commitment politically credible.”

Both experts were talking amid growing concerns over Europe’s reliance on US security guarantees, especially as the Trump administration signals its desire to lessen US military involvement in Europe.

With NATO’s future under increasing strain, Europe’s dependence on the US for nuclear deterrence has become an area of concern, particularly as President Trump has emphasised the need for Europe to “do more” in terms of its own defence.

In recent days, French President Emmanuel Macron suggested that France would be willing to extend its own nuclear umbrella to cover Europe, including Germany. Mr Macron’s proposal underscores growing unease in Europe about the shifting role of the U.S. in global security.