The three month period where the UK’s attack submarine fleet was not at sea has aroused suspicion that the US submarines were used to support the latest nuclear-armed submarine patrol. The UK has kept at least one SSBN, (a nuclear-powered and nuclear-armed submarine) on patrol constantly since 1969. The SSN fleet (which consists of nuclear-powered but conventionally armed submarines) are used to check that no enemy submarines are able to track the SSBN when it departs. However, none of the UK’s SSNs were at sea during the most recent patrol departure in late August, so what was done instead?
Until the 7th October, none of the UK’s Astute-class submarines had been to sea in five months due to a maintenance backlog. HMS Astute, which was the first submarine of the class and was commissioned in 2010, was in Faslane for five months. HMS Ambush, commissioned in 2013, has been in Faslane for more than two years, and HMS Artful, commissioned in 2016, for 18 months. HMS Audacious, commissioned in 2020, has been in Devonport for 19 months, waiting to enter 15 Dock when work there is completed. HMS Anson was commissioned in 2022, but after completing sea trials, returned to Faslane in April or May of this year and did not put to sea until 7th November.
The sixth Astute submarine, HMS Agamemnon, is currently undergoing basin trials at Barrow, and the status of the seventh, HMS Agincourt, is unclear following the recent fire in the Devonshire Dock Hall. The MOD has kept one of the older Trafalgar-class SSNs, HMS Triumph, in service. Until October, it was the most recent SSN to have been at sea, having returned to Devonport in July. HMS Triumph completed a 4-year refit in 2022, but it is remarkable that it appears to be more reliable than the entire Astute class, considering that it was commissioned in 1991. HMS Triumph is due to leave service next year.
While the Navy has some other platforms that can be used to detect enemy submarines, none have capabilities equal to submarine sonar. It therefore seems unlikely that the August patrol departure took place without a friendly submarine being present to check the approaches to the Clyde, a process known in the navy as ‘delousing’. Internal discussion in Navy circles have speculated that US SSNs could have been used to perform the task.
At the end of August the UK Defence Journal published an article claiming US submarines had been used. The following day a ‘correction’ article was published, and the title of the original piece was altered to ‘unconfirmed claims’. The Journal stated that they “were approached by several other well-placed defence personnel who expressed scepticism about the claims” and the article was changed based on “[t]heir collective expertise and inside knowledge of naval operations”. The Journal did not respond to inquiries from NIS for more detail on their reasons for issuing a correction.
The most telling piece of evidence is that a US Virginia-class SSN arrived at Faslane six days before the patrol change, and appears to have departed the night before the SSBN departure. On the balance of evidence, it seems probable that this submarine carried out the delousing process ahead of the patrol. If so, it is very embarrassing for the UK to need to call an ally because its new submarines are all out of service. Questions must also be raised about the reliability of the forthcoming Dreadnought submarines. The Dreadnought class are also being built at Barrow, and will have many common components to the Astute class, although will differ in other respects, such as reactor design.
Issues with Astute submarine availability have evidently been building for quite some time, and appear to have been compounded by a lack of facilities to carry out repairs. The Astute submarine that reportedly spent nine months on the shiplift at Faslane appears to have now been moved, but it remains to be seen to what extend reliability problems will continue to arise in the fleet.
The patrol which ended in August was another very long one, lasting just under 6 months. In October The Sun newspaper reported that on a recent patrol, provisions on board became so depleted that sweets were being rationed and medical staff were concerned about crew welfare. The story also reports that this was partially due to a plan to resupply the submarine while on patrol being abandoned. Food for the crew is a crucial limiting factor to the time a nuclear-powered submarine can stay submerged, as it can manufacture its own oxygen and water.
If Vanguard submarines are being resupplied on patrol, this would constitute a serious downgrade to standard operational security, under which submarines on patrol are not supposed to be in contact or surface for the duration of the time they are at sea. Taken with the likelihood of the US needing to assist with delousing operations, and another 6-month patrol, the UK’s ability to maintain continuous patrols appears to be seriously under threat.