Britain's strategic depth has historically come from the sea around it. An attacker must assemble naval forces capable of matching or overcoming British defenses before it can reach the country. That construction and preparation provide time without requiring Britain to surrender land. In this July 2025 assessment, existing British assets remain dangerous enough to make an attack difficult, but the fleet needs more submarines, auxiliaries and escorts.
Notable Point · 3:30:32-3:31:52
The sea as Britain's strategic depth
An attacker must build enough naval power to cross the sea, giving Britain time without surrendering territory.