In July, hackers acting on behalf of the Iranian state breached and shut down a small British power generator — a contained incident, but one that crossed a significant threshold. No lights flickered across the nation, no grid faltered, yet the intrusion confirmed what security planners have long understood: critical infrastructure is not merely a technical system but a geopolitical frontier. The UK government, reading the warning clearly, has begun the deliberate work of fortifying the boundaries that separate disruption from catastrophe.