The Royal Navy has been left without any submarines at sea to defend its surface fleet leaving a veteran to warn that "the one thing the Russians and Chinese really fear".
It comes as HMS Anson returned to its Scottish base last Friday, leaving no attack subs on patrol.
As a result, the UK's warships have no homemade underwater protection against potential threats with one former senior official describing it as embarrassing and a shambles.
He added it was brought on by years of poor planning.
The five Astute-class nuclear powered attack subs are supposed to play a lead role in defending the Carrier Strike Group off the coast of Australia.
It is understood that the US Navy is giving submarine protection for the UK's aircraft carrier HMS Prince of Wales.
Two additional Astute-class subs have remained away from the sea for more than a couple of years while another is being refitted in Plymouth.
A fifth remains in dry dock.
GETTY |
HMS Prince of Wales
A sixth sub is unlikely to be finished construction for another 18 months.
The UK's four Vanguard-class subs which are armed with long-range nukes aren't designed to attack other submarines or surface ships.
Falklands veteran Rear Admiral Chris Parry said: "The whole nuclear enterprise is a shambles."
"It's ridiculous we can't send an attack sub on deployment," he added.
GETTY
|HMS Anson returned to its Scottish base
"These submarines are the one thing the Russians and Chinese really fear."
The Royal Navy said its submarines continued to be deployed globally on operations while "protecting national interests and keeping us safe".
Meanwhile, the UK has considered deploying an army of AI-powered underwater drones to hunt Russian submarines in British waters.
The autonomous mini-submarines can remain submerged for months at a time.
In a new system called Lura, the drones effectively "illuminate" the oceans to simplify submarine detection.
Recent incidents in the Baltic Sea have seen damage to power cables, telecom links and gas pipelines following Russia's invasion of Ukraine, with many blamed on Moscow.
Defence Secretary John Healey previously ordered a Royal Navy attack submarine to surface after a Russian spy ship was detected "loitering" over critical British undersea infrastructure.
The Russian Ambassador to the UK did not deny allegations that Russia has hidden sensors around British waters.
The Lura system, developed by European defence firm Helsing, uses what is described as a "constellation" of underwater sensors to analyse acoustic data.
The technology can distinguish between two ships of the same class by detecting subtle differences in their acoustic signatures.