A US-made Long Range Anti Ship Missile (LRASM). Photo: US Military

The US Navy is rebuilding its ship-killing edge by fielding stealthier, smarter and faster missiles, a move toward phasing out the long-serving Harpoon as its primary anti-surface weapon.

This month, Air & Space Forces Magazine reported that Lockheed Martin had opened a second production line to make two of the US Navy’s next-generation anti-ship missiles, the Long Range Anti-Ship Missile (LRASM) and its air-launched variant, the Joint Air-to-Surface Standoff Missile-Extended Range (JASSM-ER).

The two missiles aim to address glaring capability gaps in America’s anti-ship weapons, particularly air-launched ones that enable standoff engagements.

Air & Space Forces Magazine reports that this ramped-up production aims to boost missile stocks that simulations have shown would be quickly depleted in a Taiwan contingency, with defense giant Lockheed Martin producing 500 LRASMs and JASSM-ER missiles a year but with plans to increase that number to 1,000 units annually.

The Warzone reported last month that the US Navy had awarded separate contracts worth US$116 million to Raytheon and Lockheed Martin to develop an air-launched, air-breathing hypersonic anti-ship missile dubbed the Hypersonic Air-Launched Offensive Anti-Surface Warfare (HALO).

The report notes that a test flight is planned in 2026 for the weapon to be fielded in 2029 on its F-35C and possibly its F/A-XX next-generation carrier-based fighter.

The HALO’s use of air-breathing hypersonic technology mirrors the decision to scrap rocket-powered boost-glide hypersonic weapon designs.

Asia Times reported this month on the US Air Force’s decision to scrap the Air-Launched Rapid Response Weapon (ARRW) project in favor of the scramjet-powered Hypersonic Attack Cruise Missile (HACM). The HACM has significant advantages over the ARRW that can carry over to the HALO project, such as a smaller size that allows it to be carried on fighter aircraft.

The failed US ARRW hypersonic weapon. Photo: Twitter

While the Cold War-era Harpoon has been the US Navy’s primary anti-ship missile for decades, it is undeniably showing its age. In a 2017 article for Naval Technology, Gareth Evans notes that the Harpoon is not fast, not maneuverable, has poor resistance to modern missile countermeasures and lacks precision guidance.  

Even with those disadvantages, Tyler Rogoway notes in an August 2018 article for The Warzone that the Harpoon Block II+ upgrade package includes a new GPS receiver and flight control system that will help the missile find its targets in complex coastal environments, a two-way datalink to allow the missile to be retargeted in flight, and a possible infrared seeker that gives all-weather capability.

Such upgrades, Rogoway notes, are standard in newer anti-ship missiles such as the LRASM and can bring the aging Harpoon to a comparable level with more modern weapons of its type.

But despite that Harpoon upgrade, Naval News notes in a November 2022 article that developments in hypersonic technology show that in high-end combat situations, subsonic offensive weapons such as the Harpoon are already overtaken by technologies based on very high speed and maneuverability.

The Harpoon may still lack the range and penetration capabilities needed for aircraft and warships to stay out of China’s anti-access/area-denial (A2/AD) bubble. 

Dmitry Filipoff, in a February 2023 article for CIMSEC, notes that the Harpoon’s biggest weakness is its combination of a short range of 128 kilometers for standard variants and the lack of meaningful inventory in all compatible launch platforms except carrier-based aircraft.

Filipoff mentions that the Harpoon’s limited range may funnel US Navy carriers closer to the main battle area, exposing these high-value assets to unnecessary risk.

He also says that since the US Navy has lagged for decades in replacing the Harpoon, this hazardous method of attacking enemy warships with carrier wings is the US Navy’s only tactic for sinking high-end warships at long range.

Given that deficiency, Janes noted last month that China’s latest HQ-9B surface-to-air missile (SAM) deployed in Woody Island has a range of at least 200 kilometers. In addition, Brent Eastwood notes in a December 2022 article for 1945 that China’s YJ-21 anti-ship hypersonic missile is believed to have a 1,500-kilometer range, which may force US carrier battlegroups to sail out further to remain out of range.

China’s YJ-21 hypersonic missile in a test launch. Image: Video Screengrab

Apart from that range deficiency, the Harpoon’s low subsonic speed and lack of stealthy design may impact its effectiveness against near-peer adversaries in an anti-access/area denial (A2/AD) environment.

In a February 2019 article for USNI News, Mary Eckstein notes that the Harpoon’s use of an active radar seeker alerts enemy shipboard defenses, with its lack of stealthy airframe compounding the chances of detection.

Although the Harpoon has a sea-skimming mode to avoid detection, Ryan White notes in an April 2021 article for Naval Post that the problem with such missiles is that sea spray degrades the performance of active radar seekers, potentially causing the missiles to crash into the water.

Ryan also notes that due to the use of active radar seekers, sea-skimming missiles are limited to speeds below Mach 3. Beyond that, ionized gases form on the missile’s surface, blocking out datalink connections.

Faced with those deficiencies, the HALO, JASSM-ER, and LRASM employ several divergent approaches from the Harpoon to defeat enemy shipboard defenses.

In the case of the HALO, Abraham Mahshie notes in a January 2022 article for Air & Space Forces Magazine that the advantage will always go to hypersonic weapons in terms of ship-killing ability, as no current defenses can intercept them reliably and that in the event of a late interception during the missile’s terminal phase, the massive kinetic energy of such weapons ensures heavy damage even without an explosive warhead.

Besides fielding hypersonic anti-ship missiles, building missiles with greater range, larger warheads and greater autonomy can help to restore the US Navy’s ship-killing edge.

As noted by Sydney Freedberg in a July 2017 article for Breaking Defense, the LRASM has a 320-kilometer range and packs a 450-kilogram warhead compared to that of the Harpoon, which weighs 221 kilograms and is designed to navigate autonomously around enemy radar and defenses.

With its onboard AI allowing it to change course without human intervention or satellite guidance, the LRASM allows it to keep comparative electronic silence while on approach to its targets.