The Nuclear Question Hanging Over Every European Security Conversation

The Iran war has forced Europe to confront the nuclear deterrence question it has been avoiding for decades. Here is why the conversation is finally happening.

For the entirety of the post-Cold War period, the nuclear deterrence question in Europe was managed through a careful combination of NATO integration, US extended deterrence commitments, and strategic silence about what European nuclear policy would look like if those commitments were tested. The formula worked because it was never seriously tested. In 2026, the formula is under pressure that is forcing the conversation that European governments have spent decades avoiding.

The pressure comes from two directions simultaneously. First, the Trump administration's explicit transactionalism about alliance commitments — its suggestion that US military support for Ukraine might be conditional, its unilateral military action in Iran without alliance consultation, its general approach to security relationships as commercial arrangements rather than strategic commitments — has raised genuine questions about the reliability of US extended deterrence for European security.

Second, the Iran war has demonstrated that nuclear weapons remain central to great power competition in ways that post-Cold War optimism had led some analysts to underweight. Iran's nuclear programme was the specific motivation for the US-Israeli campaign. The deterrence failure that allowed Russia to invade Ukraine was partly a story about the limitations of conventional deterrence in the absence of nuclear parity.

Macron's repeated suggestions that French nuclear deterrence might be extendable to European partners are not new. What is new is the seriousness with which other European governments — particularly Germany, Poland, and the Baltic states — are treating the suggestion. The conversations happening in defense ministries and foreign policy establishments across Europe about what a genuinely European nuclear deterrent architecture might look like, and whether it is even theoretically achievable, are more substantive than they have been at any point since the end of the Cold War.