Three days after the Vatican called for AI to be ‘disarmed', the Mistral CEO defended his company's defence-AI work, arguing Europe cannot afford unilateral restraint.

Arthur Mensch, the chief executive of French AI startup Mistral, pushed back directly on Thursday against Pope Leo XIV's call to “disarm AI,” arguing that European companies cannot afford to step back from defence-AI work when adversaries are actively deploying the technology.

The remarks, made three days after the Vatican published Magnifica Humanitas, the Pope's first encyclical, mark one of the most direct corporate responses yet to what has rapidly become the Catholic Church's most consequential intervention on AI.

“We're all for peace,” Mensch said, “but if you look at our rivals and adversaries in the world, they're using artificial intelligence. As long as we have adversaries that are threatening, and they are threatening, we do need to have our own capabilities.”

The Mistral CEO's framing is the structural defence of military-AI development the European tech sector has been working toward since the Ukraine war, but his decision to articulate it as an explicit rebuttal of a sitting Pope is what makes Thursday's remarks notable.

The encyclical itself is the document Mensch is responding to. Magnifica Humanitas, the 42,300-word text Leo published on 25 May, calls for the disarmament of AI, the establishment of three binding requirements around any autonomous-weapons deployment, traceability of decisions, meaningful human control over lethal action, and international rules to slow the technological arms race, and explicitly rejects the traditional “just war” theory as “outdated.”

The Pope further argued that military force can be justified only in “self-defence in the strictest sense.” The encyclical is the most direct papal intervention in tech regulation in decades.

Mensch's position contains its own theological echo. The Pope's “self-defence in the strictest sense” framing and Mensch's “adversaries are threatening, so we need our own capabilities” framing are not, strictly speaking, in contradiction.

Both accept the legitimacy of self-defence; both reject offensive use. Where they diverge is on what self-defence requires in 2026. Leo's position is that the threshold for the introduction of lethal AI is higher than any state has so far articulated.

Mensch's is that Europe cannot meet credible adversaries with that threshold while those adversaries operate without it.

The commercial backdrop matters here. Mistral has been visibly building a defence-AI portfolio since at least early 2025. The Helsing partnership announced at the Paris AI Action Summit in February 2025 produced joint work on vision-language-action models designed for “a new generation of defence systems.”

Helsing has already deployed AI systems in Eurofighter combat jets, battlefield simulations and Ukraine drone operations. Mistral has separately been pitching for defence contracts with multiple European governments.

Mensch's public push-back against the Pope is therefore not a hypothetical posture, but a defence of an existing business line that is now under formal moral censure from the Vatican.

The Pope's influence on the AI policy debate, on the other hand, has been larger than anyone expected six months ago.

Anthropic co-founder Christopher Olah appeared at the encyclical's launch, lending Silicon Valley validation to the document. The European Commission welcomed it on Monday evening; OpenAI, Google and Microsoft issued formal expressions of respect.

The Vatican is not, in any meaningful sense, a regulatory authority over AI development. What it has produced with Magnifica Humanitas is a moral vocabulary that legislators and policymakers can use, and Mensch's rebuttal acknowledges, by its existence, how much that vocabulary now matters.

The clean rhetorical contrast obscures a quieter European-policy reality. Brussels is moving toward enforceable AI-warfare frameworks but has not yet codified the kind of binding restrictions Magnifica Humanitas calls for. Member-state governments are simultaneously expanding their defence-AI procurement budgets.

The contradiction is real, and the next year of EU AI Act enforcement, member-state defence spending, and Vatican-aligned policy advocacy will indicate which side wins out.

Mensch, on Thursday's evidence, has chosen to bet his company's public posture on the defence-procurement side of that argument.