NATO’s September 2026 Quantum Technology Roadmap includes a Quantum Zero Beacon Project to demonstrate quantum-resilient communications between Brussels and Mons by late 2027, yet the core risk is that encrypted traffic collected today can be stored for later decryption once powerful quantum computers emerge.

Different national and EU transition timelines (such as EU high-risk protection by 2030 and UK milestones through 2035) create coordination challenges for multinational missions, where one partner’s upgraded path may still leave information exposed through legacy systems or contractors.

The author proposes a secrecy-horizon assessment that records each priority information flow’s required confidentiality lifetime, current protections, dependencies, and tested quantum-resistant alternatives, so readiness is judged by whether long-lived secrets were protected before interception rather than by upgrade percentages alone.

The Alliance is preparing quantum-resilient communications. Its most urgent problem is protecting information that could still matter long after today’s encryption is broken.

Imagine an allied engineer sharing a sensitive infrastructure design with a NATO partner in 2026. The document could remain operationally valuable for another fifteen years. An adversary intercepts an encrypted copy but cannot read it. Years later, NATO upgrades the connection to quantum-resistant cryptography. The new exchange is protected. The old captured copy has not disappeared.

That is a hypothetical example, not a claim that such a NATO document has been intercepted. It illustrates why the question when will a powerful quantum computer arrive? is the wrong starting point for protecting long-lived military secrets.

The relevant clock can begin when vulnerable encrypted traffic is collected, well before anyone can decrypt it. A successful cryptographic upgrade cannot retroactively prevent an earlier interception.

This is the strategic problem NATO’s newly published Quantum Technology Roadmap must confront. Released on 29 September, the roadmap includes a Quantum Zero Beacon Project to demonstrate quantum-resilient communications between NATO headquarters in Brussels and Supreme Headquarters Allied Powers Europe in Mons, with a fourth-quarter 2027 milestone. It is a meaningful pilot, not evidence that every Allied network has already migrated.

A fresh development makes the timing more concrete. On 15 October, Britain’s National Cyber Security Centre published updated guidance for using post-quantum protection in TLS, the protocol widely used to secure online connections. It advises appropriate organisations to start moving now rather than wait for a distant quantum breakthrough. The guidance is for........

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