The Navy Is Building a Hypersonic Ship-Killing Missile Called HALO
On Monday, defense giants Lockheed-Martin and Raytheon were both awarded contracts totaling $116 million between them by the U.S. Navy to separately develop prototype ship-sinking hypersonic missiles designed to sink ships hundreds of miles away for a program known as HALO (Hypersonic Air-launched Offensive). The competing initial design proposals are due in late 2024.
This likely-to-be scramjet-powered weapon, also known as Objective Anti-Surface Warfare Increment 2 (OASuW) in Navy budget documents, would be carried by the service’s carrier-based FA-18E/F Super Hornet and F-35 Lightning jet fighters and perhaps future successors. It’s expected to fly farther and much faster than the current LRASM stealth cruise missile.
The focus on anti-ship capabilities reflects the focus on a potential conflict with China in the western Pacific Ocean. Notably, simulations of a battle over Taiwan suggest it would be decided in large part by the effectiveness of long-range anti-ship missiles.
The Navy’s Need for Speedy Missiles
Strictly speaking, a hypersonic missile could describe any weapon that exceeds five times the speed of sound—i.e. traversing a mile per second—but practically, the term applies to two modern concepts. The first is a missile that releases hypersonic gliders that skip just on top of the Earth’s atmosphere.
The Navy’s current hypersonic weapon program is a hypersonic glide vehicle weapon called Conventional Prompt Strike, which, at least initially, appears primarily designed to hit static surface targets. These large weapons will be deployed in the vertical launch cells of U.S. Virginia-class submarines and Zumwalt-class stealth destroyers.
However, HALO’s approach is for a lower-flying conventional cruise missile that uses ramjet or scramjet propulsion. Such engines are extremely efficient at sustaining high speeds because they use onrushing supersonic airflow for compression instead of a compressor. However, they usually require separate boosters to accelerate them to high speeds in the first place.
The Navy currently has two premium anti-ship missiles, the very stealthy AGM-158C LRASM, and the longer-range Maritime Strike Tomahawk. Additionally, it also deploys shorter-range Harpoon and Naval Strike Missiles. All of these weapons are subsonic, meaning they fly below the speed of sound.
There are other, less-specialized guided weapons with some application against moving naval targets like the HARM anti-radar missiles, SM-6 air defense missiles, and the JSOW glide bomb. These last two weapons are supersonic, but not hypersonic.
Thus, the U.S. Navy has anti-ship missiles and will soon have hypersonic missiles—but not yet a weapon with both capabilities. Meanwhile, Russia has frequently boasted about its scramjet-powered 3M22 Zircon anti-ship cruise missile, and China has flaunted its higher-arching DF-21D and DF-26B ballistic missiles, and a ship-based version of the former called the YJ-21.
The LRASM, which is technically “Increment 1” of the OASuW program, should be difficult to detect at a distance thanks to its stealth geometry and self-defense systems. Furthermore, the LRASM benefits from guidance by both radar and infrared seekers that distinguish different types of ships, as well as jam-resistant GPS for navigation. However, due to its subsonic speed, it might be vulnerable to detection by optical/infrared sensors at close range and destruction by close defenses shortly before impact.
It’s worth noting LRASM currently has a range believed to lie between 230 to 350 miles, but likely can have that extended to 500 miles, as has already been done with the AGM-158B JASSM missile upon which it’s based. It’s currently deployed on Navy Super Hornet jet and (soon) P-8 Poseidon patrol planes, as well as Air Force B-1Bs and even from a palletized launcher designed for release from C-130 and C-17 cargo planes. It will also eventually make its way to the Mark 41 launchers on surface warships, too.
In contrast to LRASM, the Navy wants HALO to be designed for extreme speed. Cutting-edge warships tend to have powerful air defense radars and multi-layered air defense systems with dozens of missiles and multiple close-defense gatling cannons.
Having extremely fast missiles improves odds of piercing those defenses, and also collapses time to target, potentially knocking enemy forces out before they can release all of their offensive weapons.
A Navy program document claims Increment 2 is aimed at countering “2028 threats,” likely a reference to Russia and China’s powerful air defense and anti-ship capabilities, which are sometimes described as anti-access/area-denials (A2/AD) weapons due to their enormous range. Because fielding the HALO missile isn’t expected until 2028-2030, the document says an interim upgrade of the LRASM to the LRASM 1.1 standard will take place before then. The Navy already recently introduced a cheaper, land-attack-capable model called the LRASM C3.
Whether HALO’s enormous speed is truly more reliable at penetrating enemy defenses than the LRASMs slower stealth is unclear, however. But just to be sure, the Navy wants to have both options on the table.
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