The announcement of the shortlisted options for the Royal Navy’s Interim Surface-to-Surface Guided Weapon (I-SSGW) competition should be made soon. Here we assess the background to the procurement and the likely candidates.
The semi-obsolete Harpoon Block 1C (GWS 60) anti-ship missile that still nominally equips the Type 23 frigates and Type 45 destroyers has survived several attempts to take it out of service. Its current official OSD is now 2023 which should dovetail with I-SSGW arrival. However, the RN recently invited Babcock to submit a tender to continue supporting the system until 31 March 2024 with 3 additional one-year options, potentially sustaining it until 2027. Curiously, only HMS Kent among the 3 Harpoon-capable escorts assigned to the 2021 carrier strike group deployment, sailed with the canisters in place. HMS Montrose, based in the Persian Gulf is the only other RN warship currently equipped with the full set of 8 missiles.
The available budget for I-SSGW is up to £200M (excluding VAT if payable), enough to buy a modest stock of missiles, logistic and training support until the Future Cruise and Anti-Ship Weapon (FCASW) is available in 2028. (FCASW is an Anglo-French project to replace a variety of long-range missiles with new generation technology, it is unclear, as yet if it will be capable of hypersonic speeds or another subsonic stealthy cruise missile). As a critical bi-lateral international project, it is important to signal to the French that I-SSGW will only be a small purchase to cover a 10-year capability gap and does not mean the UK is losing interest in FCASW.
The I-SSGW specification states it must be “a ship-launched, have over-the-horizon anti-ship capability and a terrain-following precision maritime land attack capability.” The desire for land-strike is sound and but adds another dimension to the project. This requirement also effectively eliminates the MBDA Exocet MM40 Block III and the Boeing Harpoon Block II+ from the competition due to their limited capabilities in this regard.
“Terrain following” is a very loose description of how missiles may navigate over land and various levels of sophistication may be employed. Using Terrain Contour Matching (TERCOM) technology, active radar may be used which is more accurate and available in all weathers. A more passive method uses optical cameras to compare the terrain against a pre-programmed library using Digital Scene Matching Area Correlator (DSMAC) technology, first pioneered for the Tomahawk missile. Alternatively, a combination of inertial navigation (INS) and Global Positioning Systems (GPS) gives a basic capability but GPS may be denied by adversaries. What level of overland navigational sophistication and robustness is required by the RN is unclear.
The deterrent threat of being able to sink ships at range is the primary requirement but, recent history suggests that the need to strike targets inland will be more frequent than the need to hit ships. The RN’s limited stock of Tomahawk Land Attack Missiles (TLAM) can only be fired from submarines. On a good day, the RN is able to put only 2 or 3 SSNs to sea and they have a multitude of other pressing tasks. The RN’s land-attack capability has been used in several conflicts and is a powerful tool but may require the SSN to loiter in a suitable firing area for some time. Frigates able to attack inland targets offers greater flexibility and an alternative, if less stealthy, option.
It should be noted that TLAM is more powerful than most of the I-SSGW contenders and has a 1,000lb warhead and a range of about 900nm. The RAF’s Storm Shadow has a 450kg warhead optimised for hardened bunker penetration so I-SSGW would complete a suite of UK land-attack weapons, each with its own advantages.
The expectation is that I-SSGW will be fitted to just 5 of the 8 towed array-equipped Type 23 frigates which are a key component of the carrier strike group. It is likely the missiles would be rotated around the frigates as they deploy operationally. To accommodate the new weapon on the Type 23, they will have to be canister-launched and have the same approximate footprint of the Harpoons they replace. Although essentially a bolt-on system, it must interface with the combat management system and the ship or other platforms may need to exchange data with the missile in flight.
It is now more than two years since the MoD issued the prior information notice (PIN) inviting industry to make proposals but as of August 2021, has still to formally invite bids. It was stated in Parliament in March 2021 that “There was a healthy response from Industry to the [I-SSGW] Pre-Qualification Questionnaire and we are planning to proceed to issue an Invitation to negotiate to the down-selected bidders later this year.” Perhaps the shortlist will be announced at DSEI in September.
The time scale now looks very tight if the original timelines are to be met. First deliveries of shipboard equipment are supposed to be made by December 2022 and the missile stocks between December 2023-24. The initial support contract will be for 4 years, with the option of extending out by 9 further years which could see the system in service until 2036. The last Type 23 frigate will be withdrawn in 2035 and the missile systems could potentially be migrated to the Type 31 frigates as the Type 23s are phased out. The Type 26 will be equipped with the larger, vertically-launched FCASW.
It should be remembered that information in the public domain about the characteristics of each missile is vague and the claims made in the manufacturer’s marketing materials may be slightly misleading. Only those with security clearance can truly analyse the complex performance capabilities of each candidate and whether they meet RN criteria.
Besides affordability, each weapon will be judged on; battlefield effect, operability in different environments, munition sensitivity, system and design safety, human factors, deployability, training, sustainability and supply chain, capability resilience and reliability.
All four of these potential candidates are part of a new generation of Western missiles that cruise at subsonic speeds and are optimised for use in cluttered littoral environments. They can strike targets on land using complex attack profiles. They utilise multiple guidance technologies which minimise electronic emissions and are very resistant to countermeasures.ISSGW-Candidates-Comparison-1
Naval Strike Missile
Developed in Norway, the Kongsberg Naval Strike Missile stands out as the smallest of the options by some margin, and by avoiding the use of radar for guidance, makes it especially difficult to detect and defeat. Its main drawback is the small warhead with about half the hitting power of the Harpoon it might replace which could be a problem if trying to counter larger warships. Deployed in the littoral environment against combatants up to frigate size it would be very formidable. It has been in service since 2012 and successfully exported to several navies, notably bought by the USN for its Littoral Combat Ships and Constellation-class frigates.
The air-launched Joint Strike Missile has been developed from the NSM and can be carried internally in the weapons bay of the F-35As being purchase by Norway. Although it would have to be carried externally on the F-35B’s wing pylon, JSM would be a very attractive addition to the UK inventory.
The RN is known to have admired the NSM for some time and many commentators suggest this is the favorite to win the competition. The plan to further extend the life of Harpoon suggests the RN feels it may need to keep the weapon either to mitigate for late I-SSGW delivery or retain greater destructive power to complement the lightweight NSM, should it be selected.
RBS15 Mk 4
The latest version of the Saab RBS15 Mk 4 ‘Gungnir’ (Odin’s Spear) appears to sit in the sweet spot that gives a good balance between range and warhead size. Although the RBS15 can trace its heritage back to the 1980s, the Gungnir is a completely refreshed design that entered service with the Swedish navy in 2020 and has been selected by the German Navy.
It is arguably the most modern of the contenders and includes sophisticated electronic counter-countermeasures (ECCM) and maneuvers in unpredictable attack profiles at increased speed during the terminal attack phase, delivering a 200kg high-explosive blast and pre-fragmented warhead. The manufacturers say it has a very low maintenance requirement and a planned life of 30 years, subject to planned incremental upgrades.
In April 2021 Israel Aerospace Industries (IAI) announced they had joined with Thales UK to offer the Sea Serpent missile for the I-SSGW competition. The Sea Serpent is based on the latest Gabriel Mk 5 variant also known as the Advanced Naval Attack Missile (ANAM). IAI has a long heritage in missile development and exports, the first Gabriel variant went to sea in the early 1970s. Details of the Sea Serpent are limited but it is believed to have been loosely based on the design of the Harpoon but is considerably cheaper. IAI’s limited knowledge of the UK market is mitigated by partnering with Thales and their long experience of systems integration onto RN warships.
The Gabriel V is in service on the Israel Navy’s Saar 5 and 6 class corvettes and has also been selected by the Finish Navy. The Sea Serpent is something of a dark horse in the competition but is undoubtedly another modern and sophisticated missile designed for complex contested littoral environments.
The Lockheed Martin Long Range Anti-Ship Missile (LRASM) AGM-158C is the largest, most capable and expensive option. Based on the successful Joint Air-to-Surface Stand off Missile (JASSM-ER), it has a quoted range of up to 500km and a 1,000lb warhead. It is designed to be effective even in the most contested environments where GSP and data links are denied and is capable of autonomous targeting using its own passive sensors and AI.
LM have demonstrated a canister-launched vision but it will be launched from Mk 41 VLS cells by the USN. The air-launched version has been selected by the US and Australian Air Force.
LRASM is undoubtedly the ‘gold standard’ for Western anti-ship missiles, given its sophistication. Unfortunately, it has a price tag to match which probably makes it an outside contender for the limited budget I-SSGW. When the RN acquires FCASW it should then have something of equivalent capability to LRASM. There is also growing political dissatisfaction about the increasing amount of off-the-shelf purchases of defence equipment from the US (without similar reciprocated purchases) that may also count against LM’s offering.