As Europe continues to come to terms with both the Russian threat amid the war in Ukraine as well as the uncertainty surrounding the U.S. commitment to Europe, policymakers across the continent are urgently considering alternative deterrence arrangements. French President Emmanuel Macron has repeatedly spoken of the “European dimension” to the French nuclear deterrent and his country's willingness to open a conversation about extending a French nuclear umbrella to Europe's non-nuclear states. In July 2025, France and the United Kingdom, Europe's two nuclear powers, announced stronger nuclear coordination in the Northwood Declaration, Lancaster House 2.0, and the U.K.-France Leaders Declaration. While Britain and France have a long history of such cooperation, these announcements undoubtedly take things to a new level.
Yet, assessments of European nuclear deterrence are often inward-looking, focusing on French and British arsenal sizes and escalation options, and on reassuring European allies of French and British credibility. What adversaries think about European deterrence efforts is, however, underappreciated. As defense spending surges, European policymakers should assess whether Russia takes the French and British nuclear deterrents seriously and what capability investments make sense to deter adversaries.…
The remainder of this commentary is available on warontherocks.com.
