The Hunt for Full-Spectrum ASW

By Captain William J. Toti, U.S. Navy (Retired)

Similarly, while most of the ASW activity was focused on detecting, localizing, and “destroying” enemy submarines, many of the detection tactics that consumed nearly all of the friendly forces’ ASW efforts simply did not work. Most of the submarines remained undetected. Yet friendly forces were still achieving transitory ASW successes against submarines they had not even detected. In other words, victory could be achieved through serendipity.

So that year, the driving question became: What if we could convert this serendipity into “effectivity” and translate these accidental methods into deliberate tactics? During the Cold War ASW was dominated by the acousticians, but by the 21st century we had long since passed the point of diminishing returns on the ability to detect quiet submarines acoustically. Hence, the “sensor Über alles” approach, although still regaled by the Cold Warriors, was no longer affordable nor effective. We had to find a better way. And in so doing, it quickly became apparent that it would be helpful to take into consideration a fundamental aspect of submarine operations that most ASW theories tend to ignore: Submarines are manned by thinking human beings who, just like all others, react to outside stimuli. And while it was becoming increasingly difficult to detect a submarine, it was also true that the submarine crew usually could not tell whether they had been detected. In that we found the linchpin: It is possible to shape a submarine’s behavior even when it hasn’t been detected. That realization led to the precepts of Full-Spectrum ASW.

The Precepts

The fundamental issue at hand was this: Although it’s great fun to detect and destroy an enemy submarine, real ASW is not about detecting the submarine, it’s not about killing the submarine, it’s about defeating the submarine. This is a nuance, but it’s an important one. For example, you can operate in the vicinity of mines for months without destroying all of them. All you really need to know is that there are no mines near you, that you have a clear path. Undetected but irrelevant mines are merely a nuisance. Well, diesel submarines can be thought of as smart, somewhat mobile, mines. Most of the ships that find themselves the targets of diesel submarines can easily outrun and out-endure their nemeses.

Further, “defeating” a submarine is significantly easier than “detecting” it. Detecting any submarine that could be a threat requires a “boil the ocean” level of effort, in both technology and force structure. To defeat the submarine, all you have to do is render it irrelevant. Draw it out of firing position. Cause its fire-control solution to be wrong. Cause it to go after the wrong target. Render its weapons useless.

People generally think of submarines as having claustrophobic physical environments, and they do, but what they really have is claustrophobic sensory environments. They are very limited in what they can perceive. Using acoustics, they generally have a maximum detection range of less than 50 miles. They must be at periscope depth to use optical systems, but detection ranges are limited by a very low periscope height of eye, and so they are generally less than 15 miles. For real long-distance targeting they need intelligence or outside cueing, both of which can be denied to them by other means.

But more to the point, our Cold War remnant, sensor-focused ASW doctrine, was causing us to miss many potential opportunities for soft-kill defeat. Rather than applying our strengths against the enemy’s weaknesses, our Cold War tactics applied our weakness—open-ocean detection capability—against the enemy’s strength: stealth. An “anti–Sun Tzu” approach.

What we really needed was something our ground forces are good at: defense-in-depth. Army combined-arms tactics build kill zones, with different zones being serviceable by different types of weapons—air, indirect fire, direct fire, etc. We needed something that addressed the submarine threat from that point of view, starting before the point where the subs departed their home port. We needed—and here’s that word again—a holistic approach.

So our team of fewer than 15 people mapped out “the journey of a submarine,” considering what would be required to defeat the submarine in every phase of its journey, in every environment it transited. We brainstormed these concepts for weeks, trying to find holes and additional opportunities. What resulted was a nine-step process that we briefed to each of the numbered fleet commanders, to the Pacific Fleet commander, and to Fleet Forces Command. A tenth step was added by the Pacific Fleet commander during our murder-board session.

This doctrine became known as the “Ten Threads of Full-Spectrum ASW.” Although they are summarized here, the specific solutions for each thread are not—both for reasons of classification, and because we don’t want to stifle innovation by providing what we think is the right answer.

The Ten Threads of Full-Spectrum ASW

In the years since ASW had been “rediscovered,” Navy leaders throughout the chain of command had heightened the awareness of our ASW challenges by stating publicly, “We stink at ASW.” This was not helpful. Every time one of our admirals said this, another country bought a submarine.

The truth was that our ASW skills had atrophied. We needed to get better. But with apologies to Winston Churchill, our ASW skills were the worst in the world, except for all the rest. We have the best ground-force capability in the world, but that does not imply we should stop improving our Army and Marine Corps. So it is with ASW.

One of the most effective forms of ASW is to stop the proliferation of submarines. We have to convince adversaries that submarines are not the solution to their “American problem.” And the only way we can do that is to tell the truth: that the use of submarines by an adversary might cause some tactical damage to American forces, but that use would cause much more severe strategic damage to the interests of the nation that employs the submarines, and this strategic self-mutilation would outweigh any tactical success that nation would achieve.

Following are the ten threads.

1. Create conditions where an adversary chooses not to employ submarines.

As opposed to using submarines for intelligence-gathering, the decision to employ them in combat is a strategic decision. What we really needed to do was create the conditions where the strategic cost-benefit analysis argued against a nation using them. There are several ways to do this, most of which are not appropriate to discuss in an open forum. But it’s also important that the submarine crew understand that if they are to go up against the United States in open naval warfare, the likelihood is very high that they will not survive, that submarine warfare against the United States is a kamikaze mission. This is not dogma, it’s the truth.

It means that just as the Army and Marine Corps have demonstrated their lethality and success in land warfare, we must make sure any potential adversary understands the extreme peril they will put their submarine crews in should they choose to employ them—peril that is not counterbalanced by strategic advantage. The adversary should be convinced that the cost of submarine escalation is not outweighed by any potential benefit gained. Sadly, this message has not been conveyed effectively.

But ASW doctrine needs more than just the deterrent component, there needs to be teeth in the “defeat” components as well.

2. Defeat submarines in port.

Obviously, it’s always better to kill the archer (the home port) than the arrow (the submarine), so destroying a submarine before it gets under way, or after it returns to port for resupply, is an obvious required capability. This is also an opportunity to apply one of our current strengths—strike capability—against a weakness of any short-endurance diesel submarine—the need to resupply.

When Full-Spectrum ASW was initially pitched, some reviewers tried to get this thread dropped. The frequent argument was, “Thread 2 will not pay any dividends because all of the enemy’s submarines will be under way before the war begins.” The reply was, only half joking, “Only if their funding of maintenance is better than ours.”

Thread 2 requires no new force structure, and it has the potential for high payoff, but only if we are postured to execute. It requires the detection of alternate refueling and maintenance locations, and therefore brings with it a heavy actionable intelligence requirement.

Even if the submarines are under way before the war starts, they probably will not know precisely where to find their American targets without external direction. This leads to Thread 3.

3. Defeat the submarines’ shore-based command-and-control (C2) capability.

The ocean is a big place to look for an individual ship or strike group, even when you have a general idea of where a particular operation is taking place, especially if you’re limited to a speed of ten knots to conserve battery capacity. If we can deny submarines their non-organic (shore-based) C2 capability, this constraint becomes even more limiting. Without external targeting information, most submarines stumble around the ocean semi-blind. Thread 3 therefore requires the capability to defeat the submarine’s shore-based command-and-control system.

It requires an ability to interfere with the enemy’s submarine communication systems, interfere with the ability to pass over-the-horizon targeting information to the submarines, and affect the enemy’s decision-making process for selecting the location for operations, even if only locally.

4. Defeat submarines near port, in denied areas.

During the Cold War, one of our ASW precepts was that we would deny sanctuary to the Soviet submarine force. We would go after them deep in their own waters, almost exclusively with our own fast-attack submarines. Today we must still maintain the capability to defeat submarines within their defensive perimeter, as they are leaving (or returning to) port.

It’s important to introduce a new concept here: the “vulnerability time line.” That is the period over which the enemy submarine will be vulnerable to being defeated during any particular thread of Full-Spectrum ASW. Our “design-to” solutions must be able to respond within the vulnerability time line, otherwise they are rendered useless. In the case of Thread 4, that time line for submarines leaving port would be on the order of minutes to a very few hours. So our capability to engage enemy submarines in Thread 4 must include this kind of responsiveness. If the submarines do get under way in the early phases of the campaign, this means we will not have a lot of time to prepare the battle space. It means we have to be postured to execute Thread 4 in “enemy defensive areas,” even before actual hostilities begin.

Here we must also introduce the notion of “environment-tailoring.” In short, each defeat mechanism must be tailored to the specific real-world physical environment in which it is intended to work. A hypothetical, generic “capabilities-based” ASW solution is neither affordable nor required, because there is a limited number of countries that can actually pose a submarine threat to the United States.

Hence, the solutions we might use for the “defeat near port in denied areas” are very different from the solutions we might use for the next thread.

5. Defeat submarines in choke points.

In the real world, most adversary submarines have to transit through choke points to threaten U.S. forces. These serve as funneling locations that constrain the area we would need to search, and they are usually not in denied areas. Hence, less “survivable” solutions can be used against submarines in these areas.

A solution to Thread 5 would require both very shallow water detection and a very shallow water attack, and could employ land-based solutions of limited range (the width of the choke point). The vulnerability time line for Thread 5 is the time it takes the submarine to transit the choke point, on the order of minutes to a very few hours.

Once the submarine has transited the choke point, then we’re on to Thread 6, a domain where the ASW problem potentially becomes much harder.

6. Defeat submarines in open ocean.

Most of our post–Cold War ASW tactics and capability development, and almost all of our money, have gone into solving the Thread 6 ASW problem without context or balance.

Thread 6 is about deepwater ASW. It is where the ASW fight transitions from offense to defense. It requires the ability to conduct broad area search over vast expanses of ocean. Many of our current capabilities, including SURTASS and Low-Frequency Active Acoustic, directly (and only) address Thread 6.

Thread 6 is about defeating the submarines before they get into firing position. (While thread 6 is transitionary, the purely defensive ASW capability against submarines that are in firing position is factored into Thread 9.) The vulnerability time line for Thread 6 is the several hours to the few days required for the submarine to close to firing position.

A strong Thread 6 capability also depends on an effective ability to execute Thread 7.

7. Draw enemy submarines into ASW “kill boxes,” to a time and place of our choosing.

Repeating the theme that it’s very difficult for submerged submarines to separate the good contacts from the bad (in the absence of visual cues), conversely, it’s relatively easy to draw a submarine to the wrong “contact.” If that contact happens to be a trap, even better. The submarine must be inundated by so many “targets” that it becomes nearly impossible for it to separate the signal from the noise.

Further, if the submarine crew knows that the vast majority of targets they detect with organic sensors will be false targets intended to draw them into kill boxes specifically designed to destroy them, that knowledge will influence the crew’s behavior in many desirable ways. As with Thread 6, the vulnerability time line for Thread 7 is several hours to a few days.

So while Thread 7 aims to draw submarines away from our actual forces, it fits hand-in-glove with Thread 8.

8. Mask our forces from submarine detection or classification.

The more false targets the submarine encounters, the harder it is for the submarine to separate the signal from the noise, and the easier it is to mask the actual targets from detection or classification. Thread 8 is not about doing the impossible; it’s not about rendering large surface ships acoustically or electromagnetically invisible. Rather, it is about increasing the fog of war by making the real targets look like anything but a real target.

There isn’t really a vulnerability time line for Thread 8 because it affects our vulnerability to attack, rather than the enemy’s. Hence, Thread 8 must be a continuous process.

9. Defeat the submarines in close battle.

In 2004, most post–Cold War ASW training started at step 9 of a 10-step process. But we absolutely still need to defeat submarines in close battle—within the submarine’s weapon range. Thread 9 has a very short vulnerability time line, from seconds to a few minutes, before the submarine’s fire-control solution would support weapon engagement. Hence, the systems that allow us to defeat a submarine in close battle are very different from the systems that provide us the best capability to defeat submarines in the broad expanses of open ocean. Thread 9 includes methods to detect (and defeat) submarines as they approach their torpedo launch point. It also includes the ability to change the rhythm of battle by forcing the submarines to react to torpedo attacks, real or imagined. This leads us to the last thread.

10. Defeat the incoming torpedo.

Assuming all the previous threads fail, if a torpedo is launched, we must render it ineffective. As with Thread 9, the vulnerability time line (this time we’re measuring the vulnerability of the incoming torpedo, not the submarine) is seconds to a very few minutes.

The End Game

Over the course of the first six weeks of 2005, Full Spectrum ASW was briefed roughly 30 times to various Navy leaders. At the time, the worry was that these concepts would encounter a great deal of resistance. There were still a lot of unreformed Cold Warriors on active duty, folks who had not spent any time on modern real-world missions and just didn’t understand that the world of submarine warfare had changed significantly since the 1980s.

But as it pertained to thoughtful Navy leaders, the fears simply were not justified. Full Spectrum ASW was universally and almost immediately adopted by the 7th, 2nd, 3rd, and 5th Fleet commanders, by Pacific Fleet, and by Fleet Forces Command. Then in March that year, it was declared to be Navy doctrine by Chief of Naval Operations Admiral Vern Clark.

It was later established as the foundation of the Navy’s Global ASW Concept of Operations, factoring in issues such as the roles of various platforms, command-and-control relationships between ASW commanders, and basic tactics, techniques, and procedures.

In 2007 Fleet ASW Command morphed into the Naval Mine and ASW Command, taking on the mine-warfare mission as well. Following that transition, the new command initiated the development of “Full-Spectrum Mine Warfare” to mirror Full-Spectrum ASW.

Looking back, it’s hard to believe that the initial concepts of Full-Spectrum ASW were crafted over a period of three or four days in December 2004 by a team of fewer than 15 people. The lesson here is that properly focused, small “red-cell” team activity can make a big difference, sometimes even over short periods of time.

Captain Toti commanded the USS Indianapolis (SSN-697), Submarine Squadron 3 in Pearl Harbor, and Fleet Antisubmarine Warfare Command detachment Norfolk. He also served on the staff of the Vice Chief of Naval Operations as Navy adviser to the Joint Requirements Oversight Council, was the first deputy director of the CNO War Plans Cell, Deep Blue, and was Proceedings Author of the Year in 2001. He is currently serving as a business leader in industry.


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