As quantum computing advances, defence organisations must act now to protect national security from future cryptographic threats.

In the defence and national security space, the rise of quantum computing presents a new category of risk: the compromise of today’s encryption systems.

These systems underpin everything from battlefield communications to logistics and critical infrastructure. The moment when a quantum computer can break modern cryptography (often referred to as Q Day) may still be years away, but the urgency to act is now.

Across the defence ecosystem, many organisations lack a clear understanding of how their systems depend on cryptography. Without this knowledge, they cannot prioritise or protect the most critical assets. In response, the UK’s National Cyber Security Centre (NCSC) has issued guidance calling for a phased transition to post-quantum cryptography (PQC), with preparation milestones set for 2028, early migrations by 2031, and full readiness by 2035.

Steps to a PQC roadmap

The path to quantum resilience requires more than just technical fixes. Defence leaders must build awareness across teams, map cryptographic dependencies, and address hidden organisational debt - spanning infrastructure, process and knowledge. Integrating PQC standards while ensuring interoperability with legacy systems adds to the complexity.

It’s a multifaceted challenge, but a solvable one. Defence organisations should start by understanding their digital estate and identifying which systems will need cryptographic upgrades. They must evaluate data flows, supply chains and mission-critical services. From there, they can define a roadmap for PQC adoption, informed by standards from bodies such as NIST.

Quantum-readiness for NATO members 

Collaboration will be essential. NATO has already set a strategic direction, urging member nations to build a quantum-ready ecosystem. Defence agencies, industry partners and academic institutions must share insight, co-invest in research and train a new generation of quantum-literate professionals.

Securing the future requires the right blend of strategy, readiness and resolve. For defence organisations, achieving quantum resilience means planning for sustained change across systems, skills and strategic priorities.

DXC Technology works with defence organisations worldwide to secure systems, modernise IT estates and navigate complex change in a digital-first world. To learn more, visit their stand at DSEI - S12-300 in the Tech Zone.