The Defence Secretary has instructed the RN to conduct a study lasting no more than 6 months to assess the balance between the warships and submarines. Here we look at what might be concluded and how the balance could be changed.
Putting aside the appalling decline in overall numbers since 1970, the ratio of RN attack submarines to surface escorts has remained pretty constant between 3:1 and 4:1. The exception was in the 1980s when the submarine service reached its Cold War zenith, operating a large force of nuclear and conventional submarines, briefly attaining a ratio of about 1 boat for every two surface escorts. This was a deliberate policy, configured as primarily an ASW navy, the best way to counter the vast Soviet submarine fleet was with other submarines. Numbers in themselves are not a real indicator of fleet strength as many other factors such as the type of boat, nuclear-powered or conventional, the quality of construction, training standards etc must all be considered but this does give a rough indicator of the balance of investment. (Aircraft carriers and amphibious vessels have not been included in this assessment – after all submarines and escorts are intended to protect them. Their numbers and costs are historically rather uneven, although their procurement obviously impacts the resources available for submarines)Escorts-v-Submarine-numbers
Using some approximate unit prices for a rough comparison, it is clear the unit cost of surface escorts for the RN has actually increased relative to submarines. A Trafalgar class SSN cost around £200M in the mid-1980s while a Batch III Type 22 frigate cost £140M. At 2017 prices, an Astute class submarine cost around £1.4Bn while a Type 26 frigate is not far off at £1.2Bn. Excepting for the nuclear deterrent project, despite the effort to drive down frigate costs with the Type 31, over the last decade, and into the next, the RN continues to spend the greater proportion of its resources on the surface fleet. The aircraft carriers, and now Dreadnought programme means the opportunity to strengthen the rest of the submarine fleet is limited by funding and industrial capacity.
Although the Russian and Chinese navies have a large number of corvettes not counted in the assessment, the Chinese in particular have put greater emphasis on the undersea domain than the RN or USN. Their submarine fleet of today contains some old boats of questionable quality but this is changing fast. ‘Peaceful’ China is undergoing one of the most rapid military build-ups ever seen and its submarine fleet is no different. It has recently expanded its ‘submarine factory’ at Huludao and the PLAN is building a modern force including SSBNs, SSGNs and SSKs.
The most potent aspect of the Russian Navy has always been its submarines and it continues to invest in new boats but its moribund industry cannot deliver at anything like the pace the VMF would like. Overall the US Navy still maintains its global underwater lead with its all-nuclear SSN and SSGN fleet and invests a slightly higher proportion on submarines to escort than the RN. Of course, this assessment is uniquely skewed by the USN’s large number of aircraft carriers and amphibious platforms.
What kind of navy do you want?
If, as Ben Wallace suggests, the RN needs more submarines then it is important to be clear about their strengths and weaknesses. There is a perception in some quarters that all surface ships are just ‘targets’ that in a serious conflict would quickly be sunk in a hail of hypersonic missiles and torpedoes, meanwhile, the submarine is the unchallenged king of the seas. This is simply not the case and a navy must have platforms that can compete below, on the surface as well as in the air. Threats to surface vessels may have increased but ships carrying people and materials will still have to continue to cross the oceans and cannot be fully protected by submarines.
Submarines are a force multiplier and can be used to create the conditions necessary for sea control, allowing other forces to be effectively employed. The mere threat of a submarine will influence the actions of an adversary and they are a powerful deterrent. In a full-scale conflict they are the best means to destroy ships and other submarines and if well handled, are very hard to detect and counter. Submarines can enforce a blockade for sustained periods, denying the enemy supplies and strangling trade. A genuine submarine threat is generally going to be the biggest single headache for any naval task force commander. For example, it is believed there is currently at least one Russian SSN (in addition to two Kilo-class SSKs) operating in the Mediterranean, efforts to locate and track them consume a disproportionate part of NATO resources.
Submarine-launched cruise missiles (SLCM) provide a stealthy way to deliver precision strikes inland to open the way for others. The submarine’s ability to penetrate so-called ‘anti-access and area denial (A2AD) bubbles’, which have become too dangerous for the surface fleet is perhaps one of the areas where its advantage has increased most. The submarine can also stealthy insert special forces onto coastlines and in peacetime or lower-intensity scenarios, is the ultimate intelligence gathering platform that can listen, shadow and record the actions of adversaries.
Despite the SSN being the apex naval predator and the key high-end naval asset, there are many tasks that the submarine cannot perform. In peacetime, the submarine lacks the visible presence for reassurance and is a poor platform for maritime security, defence diplomacy or humanitarian aid that the surface fleet provides. The submarine cannot protect ships from missile or air attacks and its ASW capability would be its main contribution to protecting sea lines of communication. The submarine cannot deliver the necessary personnel numbers for Littoral Strike missions and the firepower of the submarine is overkill for asymmetric or so called ‘grey zone’ warfare. Conversely, even exquisitely expensive SSGNs cannot match the sustained weight of strikes an aircraft carrier can deliver against targets on land.
It would be unwise to believe those prophesying that new sensing technology will make the seas entirely transparent, rendering the submarine obsolete but there may be future breakthroughs that could make life much harder for submarines. The majority of effort devoted to making submarines stealthy is focused on the reduction of acoustic signatures. A range of satellite or aircraft-based sensors paired with processors powered by quantum computing able to sample vast amounts of data might be able to scan large swathes of ocean and locate submarines through tiny changes in the earth’s magnetic field or even the small changes to the water surface caused by a vessel deep below. These concepts may only exist in a laboratory for now but it cannot be taken for granted that the submarine will be so hard to detect forever. Improvements also continue to be made in conventional multi-static sonar, also harnessing the power of artificial intelligence to analyse big data sets at speeds that have operational relevance.
Essentially the attack submarine is best suited to high-end warfare where it can perform best in an offensive role, especially when given plenty of freedom to act on the initiative of its commander. There is no question that if the RN could somehow acquire more SSNs or SSKs it would increase its offensive punch with greater effect than more frigates or destroyers could achieve, making it better able to deter or defeat adversaries in a peer conflict.
Trade-offs or new money?
Ben Wallace, speaking at the commissioning of the 5th Astute class SSN, HMS Anson, said: “We’re planning on growing our surface fleet, but is our sub-sea fleet big enough? …If it isn’t, do we trade one off against the other or do we find money from elsewhere?”. This kind of assessment is needed but there are no quick fixes and the results might imply making very difficult choices. The surface fleet is already overstretched and if the RN intends to remain a credible carrier-centric navy then sacrificing a couple of Type 26 frigates or binning the Type 32 programme (for example) are not viable options. There are some radicals who would advocate navies get rid of aircraft carriers and focus on underwater forces but this philosophy is based on overstating the threat to the carriers and understating the scale of what they deliver. Submarines are a powerful asset and the RN needs more but they are not a panacea. Hobbling the carriers and their escorts to pay for new submarines would be foolish, only very significant new resources could strengthen the crewed submarine fleet and it would be a long-term project.
For the first time in decades “significant new resources” for defence are actually being talked about. The new Prime Minister says she plans to raise defence spending to 3% of GDP by 2030, this amounts to adding a whopping £157 billion over and above what was planned for the next 8 years. Such a big jump in the defence budget is arguably urgently needed but while there may be some kind of increase, political and fiscal reality is likely to make such an ambitious target difficult to attain. The alarming escalation of public debt, over-stretched public services, a commitment to tax cuts and a general election due by January 2025 seem an unlikely background to sustained rises in defence spending, despite the war in Ukraine.
If we assume for argument’s sake the RN decides it needs to increase its underwater fleet and substantial funds did become available, there are 3 main options. (1) Build more nuclear-powered attack boats, most likely by expediting and expanding the order for SSN(R). (2) Build conventional submarines, with or without Air Independent Propulsion (AIP) modules. (3) Hugely increase investment in developing a fleet of extra large uncrewed underwater vehicles (XLUUV)s.
As we have previously covered in depth in the context of the AUKUS deal to provide nuclear submarines to Australia, there is no spare British nuclear submarine construction capacity. Barrow shipyard and the vast supporting supply chain is fully occupied completing the final Astute SSNs and building the strategically-vital Dreadnought SSBNs. It would take many years to expand the infrastructure and the skills base to a point where SSN(R) construction be started sooner than the late-2030s and deliver boats much faster than the 10-year average for the Astutes. The biggest single obstacle would be growing a large workforce with the specialist experience and engineering capability to build nuclear submarines. It would be a similar story trying to expand the number of submariners when the RN already struggles to recruit and retain crews for the 10 submarines currently in commission. An emergency nuclear submarine expansion programme might be possible, but as the Australians are discovering it is very expensive and would take more than a decade and a half to deliver any effect on the frontline.
The RN dispensed with its last conventional submarines in the 1990s and now enjoys the benefits as well as the constraints of an all-nuclear fleet. An alternative is advanced diesel-electric SSKs such as the German Type 212A, fitted with AIP to enable extended periods of submersion of up to three weeks. Battery technology continues to improve, it could even supplant the complexity of AIP. Whilst lacking the global reach of an SSN, a typical conventional boat is about a third of the price to build, has dramatically lower through-life support costs and reduced crew requirements.
Smaller and more agile, SSKs are ideally suited for operations in shallower littoral waters – close to shore to deploy special forces, or in the Persian Gulf, for example – where SSN’s may be less effective. For the RN, a small fleet of SSKs would be invaluable for operations around the UK and in European waters, providing the first line of defence against foreign submarines, and providing a step-change in UK ASW capability. More boats would reduce the enormous pressure on the undersized SSN force and release them for global deployment. Small conventional boats are far better suited for training, particularly for officers to gain command experience before graduating to the SSNs and SSBNs. At present, the RN must either conduct training using its precious SSNs or rely on sending personnel to train on allied submarines. The surface fleet would also benefit from greater ASW training opportunities and a different kind of opponent.
The quickest route to acquiring SSKs would probably to purchase leading-edge SSKs from experienced builders in either Germany or Japan. Unfortunately, this would almost certainly be politically untenable so a slower and more expensive option would be to licence the designs and establish a second submarine construction facility in a British shipyard. This would involve a technology transfer and a slow regeneration of skills and infrastructure but would need to be a long-term commitment to keep a drumbeat of construction to sustain the facility beyond the initial requirement. Another thorny issue would be whether to fit the boats with UK equipment familiar to RN submariners or follow the ‘P-8A Poseidon model’, and buy directly off the shelf utilising existing foreign combat systems, sensors and weapons to save time and cost.
By far the quickest route to enhancing the existing submarine fleet would be to double down investment in uncrewed underwater vehicles. The RN has made a small start with the low-cost Manta XLUUV experimental project but this a not yet a mature technology. Besides scaling up investment in Manta and other domestic UUV projects, the RN could also partner with the US Navy in more high-end and advanced vehicles such as the Boeing Orca. Uncrewed submarines are much more affordable, have good intelligence gathering capability and can be risked in waters that manned boats would not enter. They can also lie dormant on the sea bed for long periods awaiting to be activated if needed.
The Orca-type vessel has diesel-electric propulsion and has the range to conduct patrols measured in weeks and months. Besides the land-launched UUVs deployed on independent operation, they have the potential to extend the reach of existing manned submarines. At present, the Astutes are constrained to launching small UUVs through their 21 inch torpedo tubes but SSN(R) could be designed with a bay to launch and recover much larger and more capable vehicles.
Unfortunately, XLUUVs are still a very long way from being able to replicate the capabilities of crewed submarines. A particular issue for undersea warfare is the difficulty in communicating without compromising stealth and the physical difficulties of transmitting large amounts of data underwater over anything but short distances. This makes the command and control of UUVs much more challenging than surface or air vehicles. NATO nations remain committed to keeping a human in the decision-making loop for the release of weapons. Arming the XLUUV with torpedoes, or missiles would technically be possible but reliance on automated weapon launch without communicating back to human operators is problematic. For now at least, this relegates UUVs to being unarmed intelligence-gatherers or for use in mine-laying. Like most first-generation automated and uncrewed systems, they should be seen as complementing existing crewed platforms and not replacing them.
While long overdue and highly desirable given the growing threat of peer conflict, enlarging the RN’s submarine fleet would be a long-term project with many hurdles to overcome.