The US Navy is developing a Hypersonic Air Launched Offensive Anti-Surface (HALO) missile to enhance its long-range anti-ship capabilities and transform its carrier warfare strategies.
This month, Raytheon reported completing a technical review and prototype fit-check for the US Navy’s HALO missile prototype. Raytheon describes the HALO as a carrier-based high-speed missile enabling the Navy to operate in and control contested battlespaces in A2/AD environments and support their long-range fire strategy.
The HALO missile is a crucial step in fielding the US Navy’s first anti-ship hypersonic missile, leveraging Raytheon’s expertise in hypersonics to deliver a straightforward and mature system. The prototype was created using digital and model-based engineering techniques to accelerate development, the Raytheon statement said.
Raytheon says a successful fit check on a F/A-18 was conducted in the fall, ensuring compatibility with the Navy’s Super Hornet aircraft and existing support equipment. The defense contractor was awarded a phase one HALO contract in March 2023, with work on the program currently being completed in Tucson, Arizona.
The HALO will likely replace the US Navy’s long-serving Harpoon anti-ship missile, which first came into service in 1977. While the Harpoon has been upgraded through several generations, the type may have already maxed out its upgrade potential.
In a March 2021 article for The National Interest, Charlie Gao mentions that the US Navy is set to replace the Harpoon with the Naval Strike Missile (NSM) on its Littoral Combat Ships (LCS). Gao says the surface-launched Harpoon weighs 700 kilograms, compared to 407 kilograms for the NSM.
He also notes that while the Harpoon has a bigger 207-kilogram warhead versus the NSM’s 100-kilogram one, the NSM has a programmable fuse that can select the best type of detonation for the target, while the Harpoon uses a time-delayed contact fuse. Gao says that the NSM can target an enemy vessel’s vulnerable areas to enhance its smaller warhead’s impact.
He notes that the NSM has an infrared seeker that enables it to home to specific parts of the target ship, with inertial guidance guiding the missile before reaching its terminal phase. He says that mode of guidance eliminates dependence on GPS, which can be blocked out or jammed during combat operations.
Gao says that while the Harpoon always had inertial guidance, later variants included GPS guidance to increase accuracy. However, he points out that the Harpoon’s terminal guidance relies on an active radar, which is less precise than an infrared seeker.
Gao also notes that the NSM is stealthy, with its passive infrared seeker reducing the chance of interception by shipborne defenses, while the Harpoon is not.
Despite the advantages of the NSM over the Harpoon, Gao notes that the Harpoon’s newer extended range (ER) variant may still have a lethality and range advantage of 248 kilometers versus 200 kilometers for the NSM, making it the “long arm” of US anti-ship capability.
Military + Aerospace Electronics reported in March 2022 that the US Navy announced a US$40.4 million order for Maritime Strike Tomahawk (MST) sensor suites from Raytheon to upgrade its Tomahawk cruise missiles with the capability to strike enemy ships.
Military + Aerospace Electronics notes that the MST is a stopgap solution against increasingly long-range anti-ship missiles fielded by near-peer adversaries as part of A2/AD strategies. The report says the lack of long-range capabilities to strike outside the A2/AD bubble puts US surface forces at risk.
While the Tomahawk has a 1,250–2,500 kilometer range and a 454-kilogram warhead, Jeff Schogol notes in a June 2023 Task and Purpose article that the subsonic and non-stealth Tomahawk may be unable to penetrate sophisticated Chinese air defenses protecting Taiwan invasion ships and that Tomahawk production may be unable to keep up with demand.
Schogol mentions that the MST may be suited for coastal defense roles, saying that using MSTs to defend US Marine Corps (USMC) island bases would be akin to repurposing old battleship naval guns as shore batteries for base defense.
However, some doubt that carrier-based anti-ship missiles like the Harpoon and HALO would fortify the US Navy’s surface warfare capabilities in a near-peer adversary conflict.
In a February 2023 article for the Center for International Maritime Security (CIMSEC), Dmitry Filipoff notes that the US Navy’s failure to replace the Harpoon has forced it to resort to high-risk methods to attack enemy warships at long range.
Filipoff notes that the Harpoon’s relatively short range of 128 kilometers for common variants and lack of meaningful inventory in all compatible US launch platforms except aircraft carriers threatens to place the US Navy’s most prized assets deeper into the battlespace and funnel its air wings into risky attacks.
He says that vast numbers of Harpoon missiles would be needed to sink high-end warships such as China’s Type 055 cruisers and Type 052D destroyers, bringing an offense-defense dilemma wherein committing more air power to an attack would lessen available aircraft for fleet air defense while deploying more aircraft for defense would lessen offensive power.
Filipoff also points out that the relatively short range of common Harpoon variants brings carrier-based aircraft within range of formidable shipboard defenses. He notes that while carrier-based aircraft can carry more fuel to extend their range, that would take up hard points that could be used to store extra missiles, thus diminishing firepower.
He also mentions challenges in signature reduction to prevent early detection, stressing the need to conceal the signature of carriers and their aircraft. He notes that a linear attack by massed aircraft could extend strike range but increase detectability. In contrast, he says a non-linear attack from different directions complicates mission planning and can decrease strike range.