“With the growing threat posed by Russia’s Northern Fleet and increased demand in the Indo-Pacific, the Royal Navy must overcome its submarine challenges to remain relevant,” Kaushal wrote in a new study. Too few subs and delays to essential maintenance resulting in too few deployments aren’t the only challenges, he stressed. 

Where once the Royal Navy could count on the US Navy and its approximately 50 attack boats for help patrolling Atlantic waters, the American boats are dwindling in number – and increasingly concentrated in the Pacific Ocean in order to counter a rapidly growing and modernizing Chinese navy. 

“As the size of the US submarine fleet (which is already well short of the 66 boats the US Navy requires to meet its commitments) shrinks during the late 2020s and reaches a low of 46 boats by 2030, it is not unlikely that the Pacific, where 60 percent of US submarines are typically deployed, will receive an ever larger portion of a temporarily smaller SSN fleet,” Kaushal explained.

At the same time, the Russian Northern Fleet is replacing older subs with new Yasens, each displacing nearly 14,000 tons. A Yasen is perhaps not as quiet as an Astute, but it’s bigger and more heavily armed, with ten torpedo tubes compared to an Astute’s six and vertical launch tubes for missiles, which Astutes do not have. A Yasen’s tubes can be used to launch Kalibr cruise missiles and as such it is often classified as an SSGN – a conventionally-armed cruise missile submarine – rather than just an SSN. With that said, however, an Astute can launch Tomahawk cruise missiles from its torpedo tubes, so the Russian weapons advantage is not total.

In the 2030s, the Northern Fleet should possess 10 or 11 modern SSNs, most of them Yasens. Just seven Astutes will face them. Or six, if you subtract the Astute that is supposed to be forward-deployed to Australia as part of the Australian-UK-US Aukus submarine alliance.

“In this context, the readiness of the Royal Navy’s submarines – which are, among other things, the only non-US allied nuclear submarines that regularly perform under-ice operations – is both a national and an alliance-level concern,” Kaushal stressed.

If more docks become available at the Devonport naval base – and the Royal Navy follows through with a plan to build floating docks – the British fleet should be able to keep at least one Astute at sea at all times, and surge multiple boats when necessary. Add a few American and French SSNs and Nato submarine strength will match that of Russia.

“While still considerably smaller than the Russian Northern Fleet in numerical terms, the Royal Navy can, in conjunction with other European SSN-operators such as the Marine Nationale, offset the effects of a relative reduction in US capacity and match a notional Russian force of 10 to 11 modern attack submarines which may be operated by the Northern Fleet in the early 2030s,” Kaushal wrote.

That’s all conjecture, of course. The best outcome for the United Kingdom and its allies depends on steady investment in new submarines and new support infrastructure through the next decade. 

Given the collapse in sub spending that followed the end of the Cold War, a lasting resurgence in spending is hardly a given. In fact, it would be the exception to the rule. 

But the consequences of not spending the billions of pounds the submarine service requires would be dire. The Russians would dominate the Atlantic, by dominating beneath the Atlantic.