Couple Random Thoughts on Anti-Surface Warfare

We linked to this CIMSEC piece on integrating the P-8A Poseidon with a long range anti-ship missile a couple weeks ago.

Anti-Surface Warfare (variously abbreviated either ASuW or SUW) poses a few challenges. For the most part, it is likely to take place at over the horizon ranges. That is, from a surface ship perspective, the radar horizon, limited by the height of the antenna and the curvature of the earth, is fairly short, say 20~25 miles. Ships certainly can detect threat ships at longer ranges via passive measures such as radar warning receivers, such as the SLQ-32 or the SSQ-108(V) Classic Outboard. Passive sensors alert to the presence of a radiating warship, with some fair indication of bearing (~1 degree of accuracy) and some hint of range, based on signal strength. Cooperation between two receivers can generate a fair fix depending on the baseline and environmental factors. Maybe good enough to shoot, but hardly precision targeting.

A real challenge the US faces, especially in the littorals and the Western Pacific is the density of shipping there means that enemy warships will be intermixed with friendly and neutral merchant shipping, requiring a far more precise location, and positive identification of a potential target. As LT Rusty mentioned in the comments here, the surface Navy’s thinking around the turn of the century was that an actual positive Visual Identification (VID) would be required. The obvious problem with that is, anyone close enough to VID a target is likely to get smoked with a quickness.

There are other means of generating that identification. When you think of a radar return, you generally envision a glowing green blip on a dark radar scope. But most radars today convert the raw video to a graphic symbol. Other radars, however, have modes such as Synthetic Aperture Radar (SAR) or Inverse Synthetic Aperture Radar Mode (ISAR) that uses the motion of the radar platform or the motion of the target to artificially act as a much larger antenna. Through advanced signal processing, a three dimensional picture of the target can be derived and displayed, with enough fidelity to make a positive identification.  The P-8A is being equipped with a radar capable of doing this at quite long ranges. Optical sensors capable of extremely fine resolution at long ranges are another option, though whether they are capable of near-real time use is an open question.

Ohio State University Stadium SAR Image

Another problem is SUW is the time of flight for a weapon. During the lag from launch to arrival in the target area, the target itself is moving, and often in an unpredictable manner. The seekers of anti-ship missiles have relatively small fields of view.  A missile might completely fail to acquire a target, or acquire the wrong target, either another ship in an enemy formation, or worse, a completely innocent neutral ship. One of the great shortcomings of our currently fielded Harpoon Block 1C missile is that it is completely fire-and-forget. It goes where it was told before launch, and then starts its own search.  More modern missile (including the Harpoon Block II soon to enter service) can receive updates on the target location during flight, otherwise known as a mid-course update. Of course, that requires the target be carefully tracked by the launch platform or other sensor.

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Let’s talk about a missed opportunity.  A few years ago, Raytheon and the Navy had the bright idea to take some of its large inventory of older Standard SM-2 missiles and convert them to a land attack variant, known as SM-4 or LASM (the not terribly original Land Attack Standard Missile). Using a GPS/INS guidance system similar to that on the JDAM precision bomb, the LASM would have been a fairly cheap means of augmenting the striking power of destroyers and cruisers. The program was cancelled before any were fielded to the fleet, apparently for lack of funds, and because the LASM had a rather anemic warhead, one optimized for destroying airplanes, not land targets.

As n0ted in an earlier post, later Burke class destroyers have a limited SUW capability by using their SM-2 missiles against sea targets, rather than their intended air targets. But the semi-active guidance limits them to ships above the radar horizon. A variant of SM-4 with GPS/INS coupled to a anti-radiation seeker derived from the AGM-88 HARM could have given the surface fleet a viable over the horizon ability to at least damage enemy craft, at a relatively low cost.

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The Norwegians Konnsberg seems to nicely fit the bill as a replacement for a Harpoon sized missile.

[youtube https://www.youtube.com/watch?v=bzruKeRKA4c]

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For the foreseeable future, the US Navy’s primary anti-ship platforms will likely remain nuclear attack subs and strike fighter aircraft. And that is, to some extent, fine. They both have some advantages over a surface ship in terms of their abilities to engage, and to avoid engagement.

But as the emerging “distributed lethality” school of thought is beginning to recognize, presenting the enemy with multiple dilemmas (to steal a term from the Army’s current operating concept) has the advantage of forcing him to deal with multiple threats simultaneously, which means almost assuredly one threat is not adequately addressed. Giving tactical strike fighters, maritime patrol aircraft, subs, and the surface navy a viable capability to conduct offensive SUW at long range is itself a form of deterrence that minimizes the chance that the US Navy will ever in fact have to conduct such operations.

2 thoughts on “Couple Random Thoughts on Anti-Surface Warfare”

  1. Problem with leaving SUW solely in the hands of the aviators and submariners is that carriers and subs tend to be in a lot fewer places than surface ships, owing to the limited quantities of both.

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