Countering Soviet Spy Ships - How the UK kept the SSBN force safe at sea

 

In 2025 the subject of Russian monitoring of British waters and vessels remains newsworthy. In April the Russian Ambassador to the UK confirmed that the Russians did attempt to monitor Royal Navy submarines, yet this is hardly new or novel. Throughout the Cold War, off the cold waters of Malin Head, the most northerly point of the island of Ireland, a small Soviet trawler would spend months at a time sitting and listening. Her target was not fish, but submarines. This vessel was intended to act as an intelligence collector, targeting the major US and Royal Navy submarine bases on the Clyde, to try and collect invaluable intelligence on the movements and characteristics of their submarines. The AGI was seen as a genuine threat to national security and led to a range of measures to counter its presence and protect the most sensitive national secrets.

The Russians are known to have maintained converted trawlers off Malin Head and elsewhere for decades. By the 1980s there was growing concern in the MOD about these ships and the potential risk they posed. Early AGIs were little more than converted trawlers, equipped with a range of aerials and antenna to listen to naval activity, and collect intelligence. But they were slowly being supplanted by a new generation of highly capable purpose built intelligence collection ships, that made no pretence at hiding their work.

V Boat on the Surface (Crown Copyright)

The reason why the AGI established itself off Malin Head was simple. The Irish Sea is a remarkably narrow body of water. On a clear day it is easy to see Ireland and Scotland at the same time. These relatively shallow waters are a vital transit channel for shipping, particularly Royal Navy vessels leaving the naval base at Faslane, which then transit out via the Irish Sea and into the deep Atlantic waters beyond. For a submarine, the fastest route to safety (e.g. the quiet deep) is through this channel, and then into deep water where they can vanish on patrol.

During the Cold War the Royal Navy and US Navy operated SSBN forces out of Faslane and Holy Loch respectively. There was a constant flow of Polaris and Poseidon armed nuclear submarines transiting these waters on the surface. This was also reinforced by other traffic – for example SSNs and SSKs would also sail through here, potentially on the surface.

This natural chokepoint is an intelligence collection boon for any nation, as the submarines are likely to be on the surface and moving relatively cautiously in a busy waterway. Intelligence collectors will want to gather information about the vessel, including any radiated noise, electronic signal emissions, visual intelligence and other information that will help gain information about another vessel. It represents one of the few locations where SSBNs are at their most vulnerable, at the start or finish of a patrol, as they are usually on the surface.

Similarly the deeper waters provide a valuable intelligence collection opportunity, potentially enabling the installation of covert hydrographic monitoring systems to listen out for submarines. It would theoretically be possible for the Russians to deploy some form of hydrophone array in this area, to monitor and listen out for submarine traffic, with the AGI enabling this.

In wartime this area would be even more critical, as in an early stage of Transition To War (TTW) the RN and USN would attempt to get as many SSBN’s to sea as possible to provide a strategic nuclear capability. The Russians would only have a finite period to interrupt this, but if exploited properly, it could allow them to bottle up the SSBN forces. For example, covertly laying a minefield in these waters in the run up to war, with mines programmed to explode when they detected the acoustic signal of an SSBN or SSN could potentially disrupt the entire British deterrent capability before the war even began. It is for that reason alone that in the event of war, destruction of the Malin Head AGI was seen as one of the key priorities for UK forces.

To that end, the Soviet AGI force was seen as a particularly vital target to monitor and understand, both its operating patterns and its likely capabilities. The task of understanding the AGI and its potential for harm was seen as so vital that the Cabinet Office led deterrence areas, directed that the SSBN Security Committee routinely considered it as part of their work. In other words, tracking and monitoring this single ship occupied a considerable amount of attention by the very heart of the UK security establishment.

VISHNAYA Class AGI (Copyright US Navy)

By the mid 1980s the Royal Navy had carefully assessed what it knew of Soviet deployments and concluded that the AGI force was likely to be deployed in different ways. It assessed the threat as being built around three different patrol types.

“Fixed Patrol: This is concentrated in a fixed small area to collect intelligence against a specific target or targets likely to be located in the area. The MH Patrol, off the North Coast of Northern Ireland and the Shetland Island patrols are of this type.

Area Patrol: This encompasses a wider geographical area than a fixed patrol and has a wider range of targets. The English Channel patrol is in this category.

Reactive Patrol: This entails the deployment or diversion of an AGI to take advantage of a specific collection opportunity or surveillance requirement such as the early phases of a Joint Maritime Course (JMC) deployment from the Firth of Forth to the Shetlands”.

The UK identified that in any given period there were likely to be three distinct AGI patrols conducted around UK waters. The first was the Malin Head AGI, which was usually in post from March to November most years. This period would have been sufficient to cover several SSBN patrols through the Clyde Approaches and provide time to get back to Soviet waters before the Baltic or Northern Fleet ports became icebound for the winter.

The second patrol was a near permanent presence of an AGI near the Shetland Islands to monitor naval activity in the region. This was a key area of naval interest, as many NATO vessels heading north would transit nearby, and it also housed vital radar and communication links for NATO more widely, including the critical early warning station at RAF Saxa Vord:

“AGIs are deployed to the Shetlands to monitor exercises, and associated with them, probably NATO microwave and tropsheric scatter links. The Shetlands area also sees the near permanent presence of a Soviet naval contingency tug, which supports Soviet vessels operating in the North Atlantic and probably has a limited COMINT collection while on station”.

Finally there was an AGI deployed in the English Channel that focused on both UK and French interests. The MOD assessment of this deployment was that was tasked “primarily against French SSBN operations and secondarily against UK maritime and land based activities, ranging from high-value units such as submarines and carriers operating from Devonport and Portsmouth through to fleet exercise activity sponsored by FOST, shore based telecommunication links and equipment trials”.

Clearly all three types of patrol posed a challenge, but the main MOD concern was about the Malin Head AGI, seeing it as a direct risk to the deterrent. The MOD assessment was that the AGI there was tasked with five main activities:

1.      1. Locating SSBNs in transit and transmitting this information back.

2.      2. Using hydrophones and sonobuoys to collect submarine acoustic signatures and potentially lay them covertly in UK waters,

3.      3. Moving into a position to harass, track and/or sever the towed sonar arrays of  surface transiting vessels.

4.      4. ELINT and COMINT interception of intelligence from shore and maritime based transmissions.

5.      5. Non acoustic detection using the Extra-Low Frequency Effect.

An MOD paper summed up the real risk that the MH posed to the SSBN and other submarines in the area. “The MH anti-SSBN operation is aimed at locating SSBN transits through the shallow restricted waters of the Clyde and reporting this information to other Soviet units and commands, together with collection of acoustic, electromagnetic and other non-acoustic signatures if possible. Additionally, the AGI has the ability to harass an SSBN physically and to sever non retractable towed arrays of surface submarines”.

Brought together this meant that the Malin Head AGI posed an extremely challenging threat to UK naval operations. The key risk was protecting the deterrent at any price, and accordingly the Royal Navy was tasked to put mitigations in place to ensure its security.

“In view of their strategic importance, the unique nature of SSBN operations and their status as a primary target for Soviet AGIs, there is a need to provide protection for SSBN during their shallow water transits of likely AGI patrol areas to and from their Clyde bases….Introduction of the 12 mile limit around Ireland and mainland UK has reduced the AGIs freedom of movement but not eliminated the threat from the MH patrol area AGI which continues to have the right of innocent passage through the North Channel as well as complete freedom of movement beyond the UK’s territorial waters.  To protect SSBNs in transit to and from the Clyde it is necessary firstly to accurately locate and report the position and movement of the AGI to submarines in advance of, and during their transit, whether they are dived or surfaced. Secondly it is necessary to provide protection for the submarines in the form of a vessel that can prevent physical interference by the AGI and/or mask by electronic or acoustic means the acoustic signature of the submarine”.

The Royal Navy was particularly concerned about the challenges of identifying where an AGI was at any given time. Although in popular imagination today we may think that it is possible to have a constant plot of surveillance positions and know exactly where a ship is located, in the 1980s this was not the case. There was real concern in the MOD about how difficult it was to actually find an AGI and monitor its location on any given day.

This was a challenge because if you didn’t know where the AGI was at any given time, it could be doing several things. Firstly, it could be sailing somewhere that would allow it to be present to conduct intelligence operations – for example it could covertly sail to near where an SSBN surfaced and then be present to collect intelligence on it. Secondly, if you don’t know where an AGI is, you don’t know what it is up to, and this could give it the space and freedom to conduct covert operations like laying hydrophones in UK waters. Such an outcome would have meant that a UK submarine could have sailed over these arrays, providing intelligence of huge value to the Soviets, who could then covertly recover them later on.

Identifying where the AGI was highlighted the critical importance of the Nimrod force, which was tasked to conduct patrols of the Clyde Approaches regularly when a transit was due, in order to identify the AGI and confirm its location. This would enable a decision on whether it was appropriate to transit, and in turn whether you needed to send out the ‘man marker’.

HMS SENTINEL (Copyright @navylookout)

The concept of a marking vessel was at its heart quite simple. The Royal Navy would use a vessel to monitor the AGI and stop it making a nuisance of itself. In the 1980s this task was carried out by HMS SENTINEL, a former north sea oil rig support vessel latterly converted into the Falkland Islands Patrol Vessel. SENTINEL was based on the Clyde and used to monitor the AGI when required.  The role of SENTINEL was to be sent out, to sit near the AGI and simply watch her most of the time to prevent mischief.

Marking was a surprisingly contentious topic in the 1980s, with significant internal disagreement on its value. In 1988 the then CINCFLEET wanted to monitor and mark all AGI’s all of the time but was talked out of this due to the resource challenge this would involve. Instead, a more limited approach was adopted of tracking AGI’s where possible and being present as necessary to use the marker vessel when needed.

This led to the development of Operation MUSKETRY, which was intended to ensure that HMS SENTINEL would be available to monitor the AGI when needed, or if she was not available then RMAS ROYSTERER would take on the role instead. The goal was to ensure that when certain criteria were met, the AGI would be followed. These criteria were set by the Cabinet Office SSBN Security Committee as being:

·         “When an SSBN deploys or returns from patrol

·         When an SSBN conducts a surface transit to or from a Deep Water independent exercise area (INDEX)in the Northern Fleet Exercise Areas, with or without a Towed Sonar array fitted.

·         During a number of ‘spoof periods’ for operational deception. Such occasions might include when an SSBN is conducting a dived transit to or from the NXFAs for INDEX, trials or work up.”

The challenge facing the RN though was that due to poor availability of SENTINEL and poor intelligence on the location of the AGI on any given day, there was a real security risk to the deterrent and other submarines.  This led the RN to conclude that it needed to drive significant changes to how it monitored the AGI risk.

By 1988 plans were well advanced to carry out different ways of responding to the threat. Firstly the RN would use HMS SENTINEL in her role as ‘marker’ to try and stay close to the AGI, but it would also look to replace her by vessels more suited to the task. SENTINEL was slow and while useful to run racetracks around a near static AGI, her ability to intercept in a crisis to prevent an AGI steaming for, and severing the towed array of an SSBN, rendering it totally vulnerable due to the loss of detection (as well as the potential collection opportunities this posed) was extremely concerning.

Instead the RN put forward proposals to potentially take up from trade a pair of fishing vessels that would be set up to monitor the MH AGI at all times, as well as be able to monitor the AGI in the Channel and in turn better understand the intelligence threat. They would be outfitted with a comprehensive suite of electronic equipment including ESM, hydrophones to identify when Soviet Type 15 and 75 sonobuoys (the main devices then used by Soviet navy for remote collection) were active, and in turn be able to jam them, and secure military communications. The goal of this project would have been to provide sufficient cover through HMS SENTINEL and the two trawlers to ensure that the AGI was constantly monitored, and their activities disrupted, either through presence alone, or by actively spoofing and fooling with the Soviets sonar capabilities.

At the same time the RN put in place PROJECT GOLIGHTLY, which was apparently a comprehensive electro-optical surveillance capability in the Clyde Approaches area to track and monitor the AGIs location, significantly reducing the need for physical surveillance except when required to meet the needs of the SSBN Security Committee requirements.  Had these proposals been taken up, and constant marking adopted, then the RN identified the following benefits would have been realised:

A.     “Enable sensitive trials around the UK to be undertaken in the certain knowledge that an AGI was not in the area.

B.     Allow positive warnings to be issued to trials units, establishments, firing ranges and other sensitive facilities when a threat is in their vicinity…

C.    Through close presence and constant observation, prevent or render unlikely the deployment or recovery of bottom collection devices and acoustic tracking devices.

D.    Prevent harassment, tracking and cueing of dived submarines, in particular to reduce the threat to UK SSBNs

E.      Deprive the AGI of the indicator of submarine movement that may be currently provided by the arrival of a marking vessel.”

All of these proposals made eminent sense, particularly in the late 1980s when the Soviet navy began to phase out its older AGIs and replace them with highly capable new dedicated intelligence platforms like the VISHNAYA class. These ships were assessed to have a wide range of collection measures, including sonars, and reasonable self defence measures. The Royal Navy was particularly concerned about the level of threat these new platforms would pose, particularly given earlier operations. It was noted that already AGI’s had been seen to deploy the Type 75 and 15 Sonobuoy in UK waters (intriguingly it is noted that the UK had recovered the Type 015 inside UK waters). There was concern that new platforms could contain equipment like Magnetic Anomaly Detectors, and submarine wake detection devices, as well as be able to conduct “laying of covert collection devices other than sonobuoys”.

The arrival of the VISHNAYA class in UK waters caused significant concern to CINCFLEET – in a letter from his Chief of Staff (Rear Admiral Dingemans) to the Assistant Chief of Naval Staff, Rear Admiral Livesay, it began by stating:

“In my covering letter, I expressed two fears:

·         The possibility of a Soviet VISHNAYA AGI occupying a permanent station on the Malin.

·         The use of the Soviet Type 75 sonobuoy by the AGIs for tracking our submarines.

As I write a VISHNAYA is now on station off Malin Head and will no doubt stay there until December, confirming my predictions. Of equal worry is the use of the Type 75 Buoy… The power of this buoy is shown by an event of March 17 this year when a Nimrod monitored a Bear F buoylay just south of the Iceland-Fareoes Gap. Two buoys, forty two miles apart, were holding contact on a south bound Western submarine”.

Curiously the Soviets did not conduct the same type of operations off the US East Coast SSBN ports. A Royal Navy file noted that there was no equivalent off Kings Bay, Georgia to monitor the movements of Trident submarines, although it was clear that the Soviets  were carrying out covert intelligence operations. It was assessed that the main Soviet interest instead was on naval construction and new types of SSNs and SSBNs.  For example in 1988 it was noted that at least one AGI carried out a sustained patrol to monitor the trials of USS SAN JUAN (LOS ANGELES class) and USS TENESSESE (OHIO class).

Also of note was the scale of Soviet AGI efforts to track Submarine movements more generally. In 1983 the US Navy recovered a Type 75 sonobuoy from inside US territorial waters, in Westport Massachusetts. In a note passed to the UK by the US Navy, it was assessed that:

“NAVTECHINTCEN assesses this Buoy was deployed by a Soviet AGI for intelligence collection. Buoys of this type have previously been recovered off the US East coast in late summer, since 1983. The buoys are normally modified on a Soviet AGI and deployed off a sensitive US naval base or submarine transit lane. Data from the buoys is received and refurbished by the deploying AGI. Buoys are commonly recovered and refurbished for future use. It is highly probably that there are other buoys that remain adrift and unrecovered by the Soviets”.

What changed everything was the end of the Cold War, and with this the near collapse of the Soviet naval threat in UK waters. The AGIs began to withdraw and were suddenly gone for good. With this the need for SENTINEL and the STUFT trawlers went, and the risks were dramatically reduced, as the likelihood of needing to surge SSBNs to sea in a crisis seemed to have passed. Or had it?

The lessons of the Malin Head AGI and how the Royal Navy countered it continues to matter to this day. Times have changed, and so have the means of disseminating information. Today it is much easier to track surface plot locations of AGIs as they approach our waters and operate in them. The UK continues to collaborate with NATO partners in tracking their presence – in the 1980s for example this collaboration with the French to track AGI activity near their own SSBN operating areas was known as OP DIODE. It is likely that similar activity occurs today.

Crown Copyright

The concept of ‘man marker’ continues to a point – a pair of P2000 patrol craft capable of intercepting disruption attempts are based at Faslane to escort SSBNs when needed. They have the speed and weapons to prevent an AGI potentially trying to sever a towed array if needed.

Similarly the underwater threat is recognised by the UK and other NATO nations, particularly the security of the Clyde. Part of keeping this going is Operation PIKE, which covers the route survey for the region, conducting a detailed analysis of the sea bed to determine what, if anything, has changed, and enabling specialists to track and identify any underwater changes – for example the laying of a net of sonobuoys. This is why the roles of HMS GLEANER and now HMS MAGPIE and the hydrographic branch of the Royal Navy is so vital – they may be unglamorous, but they play a vital role in ensuring the protection of the SSBN force while in transit.

The Russians continue to operate the VISHNAYA class to this day, and although now approaching 40 years old, they remain highly capable assets. They still return to UK waters regularly, and now more modern warships are deployed to protect them – this operation can be seen in  the excellent ‘Warship’ TV drama when HMS NORTHUMBERLAND was tasked to monitor an AGI off the Scottish coastline.

While the Russian navy itself may be a shadow of its former self, the threat posed by their sub sea assets, be it collectors like YANTAR or their submarine force remains a challenge. This explains why the RN has refocused assets in recent years to buy back a capability lost with HMS CHALLENGER and now restored with RFA PROTEUS, to ensure there is a national ability to monitor the seabed and recover items from it. If the Russians are meddling, the UK can and will spot it and take action to resolve it.  The lesson is clear, the Cold War may be over, but the scale of threat we face underwater is greater than ever. Now, more than ever, we need good security to protect our SSBN force from Russian ‘fishing trawlers’…