Since the commissioning of HMS Dreadnought in 1963, the Royal Navy has maintained a formidable force of nuclear attack submarines. Indeed, HMS Conqueror is the only nuclear attack submarine (SSN) to ever sink an enemy warship in anger. But the Royal Navy has undergone a transformational crisis over the past decade, shrinking in size and changing in composition. The latest nuclear attack subs, the Astute class, have become a critical component of the future of the Royal Navy—but, given Russia’s resurgence, are they enough? This article first appeared earlier and is being reposted due to reader interest. Origin The Royal Navy operated nineteen nuclear attack submarines across the course of the Cold War. As in the United States, the fall of the Soviet Union changed the requirements for the Royal Navy’s submarine fleet. The UK initially expected to build what amounted to Trafalgar Mark II boats: subs focused on antisubmarine warfare, expected to defeat Soviet submarines in the North Atlantic and the Arctic. But the collapse of the Soviet Union dramatically reduced the Russian sub threat, and created new requirements. The RN took a design pause, and eventually produced a larger submarine—one more suited to multipurpose operations, including land attack.