On October 11, 1967, the Israeli destroyer Eilat was sunk by three P15 cruise missiles fired by two dinky sixty-one-ton patrol boats of the Egyptian Navy firing from nearly twenty miles away. The realization dawned on navies across the world that long-range “over-the-horizon” missiles had replaced the gun, torpedo and aerial bomb as the preeminent antiship weapon in naval warfare. German air-launched antiship missiles had already scored some notable successes during World War II, but now it was clear that even small surface combatants could be capable launch platforms.
A decade later, the U.S. Navy debuted the AGM-84 Harpoon missile, a subsonic sea-skimming weapon with a 488-pound warhead that came in variants that could fire from a ship, a submarine or an airplane. The Harpoon still serves with dozens of countries on platforms including Type 209 submarines of the Turkish Navy, modified Fokker 50 airliners of the Singaporean Air Force and early-model Arleigh Burke–class destroyers of the U.S. Navy. The land-attack SLAM-ER variant remains an important standoff weapon for Navy fighters. The antiship Harpoon has also seen action in a number of naval skirmishes, sinking several missile boats.
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However, the Harpoon’s striking range of seventy to 150 miles (depending on type) has fallen far behind competing antiship missiles. Quite simply, after the end of the Cold War, Russian and Chinese surface-warfare capabilities appeared modest, so the U.S. Navy became preoccupied with planning for littoral operations . Even harpoon-launch capabilities were removed from Oliver Hazard Perry–class frigates and U.S. attack submarines, and not built into later Arleigh Burke–class destroyers. Navy surface warships did eventually gain the capability to use longer-range SM-6 missiles against both air and sea targets, but these employ a small 140-pound warhead, less optimized against large ships.
Meanwhile, Russia and China developed antiship missiles that outranged their U.S. equivalents, many of them specially designed to overcome anti-missile defenses using supersonic speed and evasive maneuvers. Notable examples include the Russian ramjet-powered P-800 Oniks cruise missiles (capable of streaking at naval targets up to 370 miles away while flying two-and-a-half times the speed of sound); the Russian-Indian BrahMos, which weighs six thousand pounds and performs an S-shaped evasive maneuver before impact; and the Chinese YJ-18, derived from the Kalibr cruise missile, which accelerates to Mach 3 on its terminal approach.
Enter the LRASM
The Navy has finally pushed into production a next generation surface-to-surface missile under its “Offensive Anti-Surface Weapon” program—by adapting a weapon already in use with the Air Force. The AGM-158 Joint Air-to-Surface Standoff Missile is a stealthy and highly precise surface-skimming cruise missile with a range of 230 miles, or 620 for the Extended Range AGM-158B. The shorter-range AGM-158A model saw its combat debut on April 4, 2018, when two B-1B bombers launched nineteen of the stealth missiles at a Syrian research center in Barzeh.
Lockheed Martin went ahead and developed the antiship AGM-158C model, designated rather plainly by the Navy as the “Long Range Anti-Ship Missile.” Rather than a Russian-style supersonic missile that’s too fast for a ship’s defenses to intercept, the LRASM is the missile an enemy vessel simply won’t see coming until too late. The missile retains the basic model’s inertial and jam-resistant GPS navigation system, its high-efficiency F107 turbofan engine and its thousand-pound penetrator/fragmentation warhead—more than twice the weight of the Harpoon’s.
However, unlike the ground targets the JASSM was designed to destroy, ships are mobile. Therefore, the LRASM carries multiple sensors allowing it to autonomously search for and identify adversary warships, while sorting out civilian, friendly or low-priority enemy vessels, by matching their radar profile to data in an onboard database. The missile also transmits data, including day/night camera feed, back to its launch platform via a two-way data link, which allows the launcher in turn to feed it during course corrections.
An LRASM is first fired using targeting data from the firing platform towards its target, which it approaches at medium altitude. However, if the data link is disrupted the missile’s guidance algorithm allows it to acquire and home in on a target without external direction, or to maneuver around neutral or hostile ships that interpose themselves in its path.
Guidance of the missile is handed over to a radio-frequency sensor (or Electronic Support Measure) as soon as an appropriate target enters range. Rather than exposing itself by using its own radar to search for a target, the missile stealthily homes in on an enemy adversary’s radar signals—the very radar intended to warn the target of a missile attack.
In the terminal stage, the missile descends to skim low over the ocean’s surface, and the RFS seekers hands over guidance to an infrared sensor which has sufficient fidelity to target specific locations of an enemy vessel to maximize damage. If multiple LRASMs are inbound on the same target, their networked software allows them to time their terminal approach for a simultaneous swarming attack, helping them oversaturate enemy defensive fire. The LRASM also dispose of electronic counter-countermeasures (ECCM) to overcome enemy defense systems.
All these systems do add a few hundred pounds to the missile, leaving it with a decreased range of at least 230 miles, though some sources suggest it may actually reach up to 350 miles.
The AGM-158C is entering service in 2018 with the Air Force’s B-1B bombers. The Navy’s carrier-based FA-18E or F Super Hornet jets will follow in 2019, and a few years later it will enter service with cruisers and destroyers equipped with the ubiquitous Mark 41 Vertical Launch System, which can pack a wide variety of munitions in its launch “cells.” The surface-to-surface LR-ASM variants would be fitted with Mark 114 rocket boosters which hare jettisoned after launch. You can see a surface test launch here.
For smaller frigate-sized vessels that don’t use the Mark 41 VLS (in U.S. service, Littoral Combat Ships or some future FFG(X) design), Lockheed Martin is developing a deck-mounted canister-launched version—though the U.S. Navy has chosen the cheaper, shorter-range Norwegian Naval Strike Missile to fulfill this role for now.
LRASM and Naval Strategy
All in all, the LR-ASM could significantly improve the striking power and reach of U.S. surface warships, and fits well with a new doctrine of “Distributed Firepower,” which emphasizes networking sensor data and spreading firepower over multiple launch platforms. Furthermore, the missile’s redundant guidance systems would remain effective even in a heavy electronic-warfare environment against a tech-savvy opponent. There are a few caveats to consider, however.
Long-range missiles can only be used to their fullest potential when combined with equally long-range sensors feeding targeting data to the launch platform—not something that can be taken for granted . Fortunately, between drones and aircraft capable of networking their sensor data, such as the F-35C stealth fighter and new Cooperative Engagement technology under development, the U.S. Navy has prospects for executing such a strategy.
A second consideration is that while the stealthy LRASM may evade radar direction and delay response of antiaircraft defenses until too late, its subsonic speed may leave it a comparatively easy target for shorter-range close-defense autocannons and heat-seeking missiles—though the LRASM supposedly has a reduced infrared signature.