A gap in the shield – the cruise missile threat to the UK

There is a growing conventional threat to the UK mainland that has received little attention and for which there is very limited defence. Adversaries are increasing cruise missile numbers and capabilities. Air and surface-launched missiles would be difficult to counter but submarine-launched cruise missiles are particularly potent. Here we consider the threat and how the UK could respond.


With no warning, on 13 June 1944, 8 people were killed near a railway bridge in the East End of London when it was hit by a new kind of weapon. The German V-1 was a crude, virtually unguided flying bomb but it heralded the era of the cruise missile (CM). Although there were some successes in shooting down V-1s, over 9,500 were launched at London and a large number hit the city, resulting in at least 6,000 deaths. The V-1 attacks were soon followed by the arrival of the world’s first ballistic missile, the V-2 rocket. Despite considerable efforts by many nations, more than 75 years later, no fully effective defence against this kind of weapon has been developed. As was the case in WWII, the best answer is to destroy the missiles before they can be used but mobile and covert launching platforms make this increasingly difficult. Besides the logistical and intelligence gathering challenge, this solution cannot mitigate against a surprise attack.

By the early 1990s, the US had perfected the guidance of cruise missiles to a point where accuracy could be measured to within a few metres. The Tomahawk Land Attack Missile (TLAM) used in the first Gulf War demonstrated this ‘wonder weapon’ to the world. Precise targeting of military sites and command centres helped shorten the war while minimising civilian casualties / ‘collateral damage’. At least 2,100 TLAMs have been fired in anger since 1991, at Iraq, Bosnia, Afghanistan, Somalia, Libya, Syria and against various terrorist training camps. The RN acquired a stock of TLAM from the US in 1998 and these submarine-launched cruise missiles (SLCM) remain an important UK capability, in service with Trafalgar and Astute-class boats.

While the US may have refined and demonstrated the value of precision cruise missiles in combat, Russian industry was not far behind. With a vibrant and diverse missile development programme, the Russians have achieved parity and exceeded Western missile technology in some areas. The Chinese are on a similar path and Western nations are behind in their attempts to field the new generation of hypersonic missiles. Export versions of sophisticated cruise missiles are now within reach of many smaller nations and their proliferation presents an increasingly complex threat across the globe.

The Russian Kalibr SLCM. This is the 3M-14E export variant sold to China, India and possibly Iran to arm their Kilo-class submarines. (Photo: Vitaly Kuzmin)

Exposed underbelly

Britain developed the world’s first integrated air defence system in the 1930s which proved to be one of the main keys to victory in the aerial defence of the UK in 1940. A chain of radar stations would send the location of incoming raids to a central command centre that could best position fighter aircraft to intercept enemy bombers.

Although a fraction the size, UK air defence today works on a very similar model. A series of Radar Heads provide coverage of UK airspace which are fed to the Air Surveillance and Control System (ASACS) at RAF Boulmer. A handful of Typhoon aircraft are held at readiness on Quick Reaction Alert (QRA) to launch against any intrusion or suspicious aircraft detected nearby or entering UK Airspace. The Typhoon is exceptionally effective when up against small numbers of manned combat aircraft but may struggle to detect small low-flying targets, although its AMRAAM and Meteor missiles are designed to engage CM.

The CM has the natural advantage of being smaller and far harder to detect than manned platforms. Flight profiles may vary but at least in the terminal phase, the weapon will adopt a low-level terrain-hugging trajectory making it difficult to detect by ground-based radars. To kill the CM it must first be detected and when sea-skimming or terrain-following only sophisticated airborne or space-based sensors able to distinguish against background clutter have much hope of providing coverage over a large area.

The sophisticated nature of logistic support for modern weapons platforms makes their bases and infrastructure expensive and difficult to disperse or duplicate. There are many facilities that represent a ‘single point of failure’. For example, by centralising the RN’s entire submarine force at Faslane, a few well-aimed missiles could quickly remove the ability to sustain submarine operations. Only a tiny handful of UK’s military sites have below-ground-bunkers or hardened shelters. The vast majority of buildings that support the RN, Army and RAF are above above-ground and even underground facilities may be vulnerable to modern penetrating munitions.

There are 3 main types of scenario for CM strikes. The terror attack – such an assault might not necessarily be a prelude to full-scale war but be a kind of state-sponsored high-grade terrorism. This might be designed to cause fear and chaos through mass casualty events, perhaps by striking sports venues, railway stations, schools or hospitals. The economic attack – designed to interfere with economic activity by striking at transport, utilities and government infrastructure. For example, knocking out just a few railway and motorway bridges could cause substantial supply problems for an economy that runs on a ‘just enough, just in time’ system. The vulnerable docks and ports of the UK are also critical to the economy, for example, Felixstowe alone handles 48% of the country’s container trade. Destroying a few power stations (nuclear or otherwise) would be another effective way to bring a nation to a standstill with widespread blackouts. The military attack would be a prelude to full-scale conflict, using CM initially to disable radars and air defence systems, making it easier for conventional aircraft to follow on with attacks airfields and naval infrastructure.

The almost universal vulnerability to cruise missiles was clearly demonstrated in September 2019 when, despite having sophisticated US-supplied air defence assets in place, in Saudi Arabia was unable to prevent an attack by cruise missile and ‘armed drones’. The Abqaiq oil processing facility in Buqyaq was heavily damaged and this single strike by Iranian-sponsored Houthi rebels halved Saudi oil output and reduced world production by 5%.

  • The battlecruiser Admiral Nakhimov will become the most powerful surface combatant in the world when she emerges from a major modernisation programme in 2022/3. Cruise missiles are becoming the Russian Navy’s main weapons, Nakhimov will have 174 VLS tubes for a mix of Zircon hypersonic CM and Kalibr LACM or Onniks ASCM. (Photo Sevmash)

  • The Russian Kilo-class submarine Krasnodar seen from HMS Tyne in the English Channel (July 2020). Stealthy and difficulty to detect, these SSKs are suited to operating in shallow waters such as the North Sea and are able to carry 4 Kalibr LACM. Kilo-class submarines have demonstrated their capabilities in anger by launching missiles from the Mediterannean at targets in Syria.

  • Russia’s mighty SSGN – the Oscar Class submarine. Originally designed by the Soviets as a ‘carrier killer’ and armed with 24 heavyweight P-700 Granit ASCM. At least 6 of these boats have been modernised and can carry up to 72 Kalibr LACM or P-800 Oniks ASCM (Photo: US Department of Defense)

  • A Russian Tu 160M ‘Blackjack’ intercepted close to UK airspace by RAF Typhoons (May 2018). The Russian strategic bomber force is armed with the very long-range Kh-10 Raduga ALCM which can be armed with conventional or nuclear warheads and has a reach of at least 2,880km (the Russian Ministry of Defense claims 4,500 km). This stand-off weapon could be launched at the UK without even leaving Russian airspace.

Archers and arrows

Submarine-launched Cruise Missiles are of the most immediate concern for the UK and are one of the prime reasons why investment in ASW has never been more important. SLCMs launched close to the coast offer reduced warning time or chance of detection than if air or land-launched. The Russian navy fields a variety of SSKs, SSNs and SSGNs that are all armed with modern SLCM. On paper, the Oscar class SSGNs are most formidable armed with up to 72 missiles. It should be noted that an almost stationary SSGN launching a sustained volley of SLCMs would rapidly become vulnerable to detection. It would be tactically advisable to launch just one or two missiles at a time and then go deep and evade before re-positioning some distance away to make further attacks.

The two Russian naval CMs of particular note are Kalibr and Zircon. The Kalibr (NATO name SS-N-30A ‘Sizzler’) is a modern Tomahawk equivalent with an anti-shipping variant and a land-attack version as well as various export models. With an estimated range between 1,500 to 2,500 km, it has become the mainstay of the Russian Navy’s strike capabilities and has been demonstrated for the benefit of Western observers and potential export customers against targets in Syria.

If it works as advertised, the hypersonic (Mach 8-9) 3M22 Zircon (NATO name SS-N-33) cruise missile represents a major escalation in the level of threat. This weapon can fly a low level or follow a semi-ballistic trajectory for longer ranges. It is uncertain, but its extraordinary speed may make it almost invisible to conventional radar and extremely difficult to intercept using existing missile defences. Zircon will initially be carried by Russian warships but may also arm SSGNs and potentially poses a serious threat to both ships and land targets.

The Russians have sensibly elected to design even their smallest modern combatants to be CM-capable. The 950-tonne Buyan-M corvettes have 8 strike-length VLS cells capable of launching Kalibr (The main image above shows RFS Grad Sviyazhsk class firing from the Caspian Sea against Syrian targets, October 2015). In contrast to the majority of European combatants, this provides great tactical versatility for the Russian fleet which may not be able to prevail in a direct naval confrontation with NATO but can put at risk both land and sea targets from considerable range.

In 2010 Russian arms manufacturer Morinformsystem-Agat JSC revealed a containerised version of the Club-K cruise missile (a forerunner of the Kalibr). Four missiles are hidden out of sight horizontally in a standard shipping container until the tubes are hydraulically raised for firing. Transported on an innocent-looking merchant ship, this is a potential way to mount a sudden attack on unsuspecting warships or land targets. Which nations may have purchased or operate Club-K or equivalent is unclear, but the potential for asymmetric attack or first strikes is obvious. Since thousands of container ships ply the world on a daily basis this modern-day ‘Q-ship’ is a perfect disguise, although in peacetime raises some legal questions about the neutral status of merchant shipping.

Most cruise missiles have interchangeable payloads and can potentially carry nuclear warheads or conventional explosives. In a sub-nuclear conflict, the scale of devastation caused by each missile could also be vastly multiplied by adding chemical, biological or radiological (‘dirty bomb’) contaminants. As the Russian government appears to be quite willing to authorise the careless use of Novichok nerve agent to attack its own citizens, it can be assumed they would have few scruples about employing this appalling kind of assault on their adversaries.

Although the most immediate CM threat to the UK would appear to be from Russia, the Chinese navy is rapidly becoming a global force. It is not inconceivable that in future their CM-equipped submarines and carrier strike groups could be deployed within range of Europe. Using conventional delivery means, Iran lacks the ability to hit European targets but CMs placed covertly on container ships could provide an opportunity for modest asymmetric attacks.

The British Army’s Sky Sabre system enters service this year. (Left) The 8-cell ‘Land Ceptor’ / CAAM missile launcher vehicle. (Right) the SAAB Giraffe radar which has a range of around 120km. (Photo: MBDA)

The slender shield

At sea, the RN’s Aster and Sea Ceptor systems are designed to cope with CM missile attack, in effect warships move around with their own integrated air defence bubble. With sufficient warning, RN vessels could be positioned offshore in an attempt to protect the mainland from CM but warship numbers are limited, the threat could come from almost any direction, and their radar horizon does not extend far. Situational awareness of high-level UK airspace is good, (so long as the vulnerable radar heads are destroyed by CM) but only sophisticated airborne or satellite-based radar could provide the wide coverage need to track inbound CM. The RAF has just 4 E-3 Sentry AWACS aircraft (being replaced by 5 Wedgetail AEW1), way short of the numbers that would be needed to provide round the clock overwatch of the whole of the UK.

Assuming CM could be detected, targeting data would need to be rapidly passed to a nearest hard-kill system. Unfortunately, such assets are very limited. There are no surface to air systems (SAM) permanently allocated to the defence of the UK mainland, the only British territory with any kind of integrated radar and SAM system is the Falkland Islands.

The British Army is about to commission its £148M Sky Sabre Air defence system, which utilises the same soft-launch CAAM employed by the RN’s Sea Ceptor. Sky Sabre represents the UK’s best hope of countering CM in flight. Manufacturers MBDA, claim its RF seeker has excellent clutter rejection capabilities enabling it to engage cruise missiles, UAVs and guided munitions. CAAM has an official effective range of 25km although it is widely believed to be much greater. Detection is provided by the high-definition Saab Giraffe Agile Multi-Beam (AMB) 3-D radar mounted on an extending mast to ‘see’ above trees or buildings so as to maximise its range against low-level targets. Israeli experts, Rafael are providing the Modular, Integrated C4I Air & Missile Defense System (MIC4AD) link the sensor to the missile cells and provides command and control. Sky Sabre is mobile and easy to conceal, units can operate on a standalone basis or be networked together to target over-the-horizon threats.

Sky Sabre will typically be employed to protect Army formations or forward airbases and the 24 sets being purchased are a fraction of what would be required to establish a protective umbrella over the many vulnerable military and civilian sites in the UK. To provide comprehensive in-depth defence, particularly at high-value sites or where radar range is constrained by the environment, Sky Sabre might need to be backed with additional short-range systems such as radar-directed canons or Starstreak HVM batteries.

A Royal Navy Submarine launches a Tomahawk Land Attack Missile which can hit targets around 1600 km away to an accuracy of about 5m.

Defend or deter?

Since the Soviets exploded their first nuclear weapon in 1949, the long-standing nuclear threat to the UK has been mitigated by the ability to respond in kind. If serious about countering the lethal, but non-nuclear CM threat, there are essentially two expensive choices. A defensive strategy would require the development of an extensive multi-tier integrated air defence system (IADS). A more credible conventional deterrent would demand a big increase in lethality, stocks and delivery systems of UK CM so any adversary contemplating an attack would understand they would face an equally devastating response.

The defensive strategy comes with several significant drawbacks besides the considerable cost. However well prepared, multi-layered and sophisticated, the advantage always lies with the attacker, able to choose the time and route for the strikes. It is likely at least some missiles will still find their targets and this is especially true, as hypersonic CM, hypersonic glide vehicles and ballistic missiles proliferate. There would also be a major political and perception problem if a large number of SAM batteries started to spring up all over the country. Like so many facets of defence, it would be a hard sell to persuade the public that the cost and upheaval was justified against an unseen or little-understood threat. A nation literally bristling with missile batteries around cities and civilian sites is not a good look, at least until the outbreak of hostilities.

To act as a deterrent, currently, the UK has two LACM in service – the Tomahawk UGM-109 SLCM and the Storm Shadow ALCM. TLAM can only be launched from the RN’s very small SSN force. The Astute class has storage for up to 36 TLAM or torpedoes, although no submarine captain is likely to want to go on patrol without at least a few Spearfish. UK stocks probably number about 100 rounds of Block III and IV TLAM. Assuming two boats, can be on operational patrol at any one time, theoretically, the UK could launch an ‘all out-effort’ of about 50 TLAMS before returning for reloading and a second and final wave of another 50. TLAM is relatively old and is being superseded by the stealthier JASSM and highly accurate SLAM-ER, although the US can’t bring itself to close the production line quite yet. Such claims should be treated with much scepticism but Russia says that its air defence systems installed in Syria have shot down 71 of 103 CM launched by the US, UK and France.

Unusually for UK complex weapons, the stock of Storm Shadow is relatively healthy, thought to be around 900, although some were expended in Libya and Syria. Storm Shadow has proved to be as effective as TLAM but can only be launched by the RAF Typhoon and has a warhead optimised for bunker-busting. The weapon has a range of around 500km but the non-stealthy Typhoon would be very much at risk if attempting to penetrate the advanced IADS that covers western Russia. Weapon range is a critical factor when contemplating a strike on many targets. To reach Moscow, one of the world’s better-protected cities, would require an SSN to enter the unfavourable operating conditions in the Baltic Sea to launch a TLAM.

The Anglo-French FCASW (Future Cruise and Anti-Ship Weapon) project is currently underway and is supposed to produce a new cruise missile to replace Storm Shadow and solve the RN’s anti-ship missile problem. There already appears to be a slight divergence between the French, who favour a larger, hypersonic solution, while the UK is more partial to smaller, slower and more stealthy designs. A 2018 Parliamentary report congratulated everyone on this great multi-national co-operation and its importance to industry but unfortunately this project will not deliver any kind of operational capability for at least a decade. While the Russians, Indians and Chinese are about to field Hypersonic weapons, the leisurely FCASW project demonstrates the complacency in European capitals about the growing missile gap.

If the full potential of UK Carrier Strike capability against peer adversaries is ever to be realised, then the F-35 needs to be equipped with a long-range stand-off weapon. There are no plans to integrate Storm Shadow on the jet. F-35B will very heavily reliant on its stealth if forced get up close with adversary air defences to deliver its current selection of short-range weapons.

When the first Type 26 frigate finally becomes operational in 2027 the RN will, at last, have 24 Mk41 VLS cells on a surface combatant that could be fitted with TLAM, child of FCASW or another LACM. At present, there are no plans in place to purchase any weapon for the VLS which may initially enter service armed with fresh air. In the current climate, it is also hard to imagine the Type 45 destroyers will ever be retrofitted with 16 strike-length VLS cells that their design could still accommodate.

It is interesting to speculate about who should lead an effort to redress the UK CM vulnerability. Should it be the RN as any attack will either originate from the sea or will have to cross it? Is it one for the RAF in-tray as it is primarily an air defence problem or should it become an Army priority to take a bigger lead in defending the mainland? Whatever the solution, it is another complex multi-dimensional threat that should be considered as part of the on-going defence review. Now as much as any time since WWII, perhaps the best defence remains NATO unity. If adversaries believe that all NATO members will continue to uphold the principle that “an attack on one is an attack on all” then the deterrent effect of the combined weight of firepower is the best hope for peace.