Key point: Submariners will no longer be as exceptional as before.

S’pose Bryan Clark has it right. The Center for Strategic and Budgetary Assessments (CSBA) analyst and retired U.S. Navy commander postulates that a technological revolution is about to overtake undersea warfare, rendering the wine-dark sea transparent to hostile antisubmarine (ASW) forces for the first time. This would be a bad thing from the standpoint of U.S. naval mastery. It would place in jeopardy America’s capacity to execute an ambitious foreign policy in distant waters, preside over the liberal maritime order, or accomplish all manner of worthy goals.Such matters were much on my mind while careening down I-95 to the submarine base at Groton, Connecticut last week, there to commemorate the anniversary of the Battle of Midway. The event took place on the pier where USS Nautilus—the United States’ and the world’s first atomic submarine—lies berthed as a nautical museum. Earlier this year the silent service marked the sixtieth anniversary since the day when Nautilus’s skipper first radioed home: “Underway on nuclear power.”

That signal heralded a new age in undersea combat—the age our doughty CSBA analyst contends is giving way to another new age. The advent of naval nuclear propulsion let these newfangled craft remain underwater for long stretches of time. It spared them the need for regular refueling. Machinery needed little sustenance apart from routine upkeep and overhauls. Stores such as food and other necessities for the crew became the chief limiting factors on nuclear boats’ voyages. For the first time submarines became true denizens of the deep, as opposed to surface ships able to submerge temporarily.

Nuclear power, moreover, shunted the competition between subs and sub hunters—what Clark calls the “hider-finder” competition—into the acoustic realm. No longer could anti-submarine forces count on finding enemy boats cruising on the surface, lurking just below the surface with a periscope or snorkel peeking above, or using radio or radar with their telltale electromagnetic emissions. They could hide more or less indefinitely.

(Note: This appeared in June 2015 and is being reposted due to reader interest.)

Sound, then, is the chief limiting factor on stealth. Sub designers and crews go to elaborate lengths to keep machinery and other sources of noise quieter than an opponent’s passive sonar—sophisticated listening devices, and any navy’s ASW tool of choice—can detect. A quiet boat is an elusive boat. It can prowl the depths, prey on fellow subs or surface craft, or project power onto hostile shores. But, writes Clark, Big Data coupled with non-acoustic detection, tracking, and fire-control technology may soon expose American boats to the prying eyes of hostile forces.

For instance, ASW hunters could look for minute disturbances a submarine makes to its tactical surroundings. The most hydrodynamic hull makes a wake as it travels through water. Engineering plants discharge heat. Undersea craft may interfere with sea life as they pass. Finding such traces of an American sub’s presence—and parleying that information into actionable tracking and targeting data—would nullify its core advantage in whole or in part—namely its ability to vanish beneath the waves. A visible boat is a vulnerable boat. The competition between hiders and finders could swing decisively in favor of super-empowered sub finders after six decades of supremacy for the hiders.

(This first appeared in February 2017.)

That leaves the silent service—where, precisely? Struggling to stay abreast of the times, one suspects. That’s how beneficiaries of a congenial status quo commonly respond when change shakes their world. Paradigm shifts are agony for entrenched cultures. Stakeholders in the ancien regime resist believing that shifting circumstances have rendered old ways partly or wholly moot. Oftentimes they fight against unorthodox methods that are better fitted to the times. Progress is fitful and uncertain. Strategic innovation tends to lag behind events.

How can the silent service stay in tune with the times? First and foremost, by acknowledging the danger posed by foreign navies toting gee-whiz gadgetry. Clark hints at how hard adapting to more transparent seas could prove: “unless U.S. forces adapt to and lead the new competition, the era of unrivaled U.S. undersea dominance could draw to a surprisingly abrupt close.” That’s a grim prognosis in itself. Abrupt change begets major traumas in big institutions like navies. It’s hard to get ahead of the process.

Yet while change may come quick, many of Clark’s recommendations have long lead times. If anti-access is indeed diving underwater, it may behoove sub skippers to remain farther offshore—much like their brethren skimming around on the surface. It also may behoove the silent service to reimagine its boats as underwater aircraft carriers—except that they’ll operate fleets of unmanned undersea vehicles (UUVs) rather than airplanes, helicopters, and drones.

Makes sense, doesn’t it? The mothership stands off in relative safety while smaller, more elusive, less expensive craft do the hard and dirty work inshore. But the devil, as always, lurks in the details. Clark urges the sub force to construct larger nuclear-powered attack boats (SSNs) with the capacity to handle UUVs in significant numbers, not to mention new self-defense weaponry like ultralightweight torpedoes. Yet the U.S. Navy has cast its die with the medium-sized Virginia-class SSNs now joining the fleet. No replacement will enter service until 2044 according to current plans. Shipbuilding patterns, then, imply that bigger platforms don’t lie in store for the silent service. Not without a tectonic shift in priorities, at any rate.

Meanwhile, the navy is already staring a shortfall of attack boats in the face even without undertaking a major redesign of the submarine fleet. Technological transformation, in short, could outpace shipbuilding programs predicated on longstanding assumptions about combat in the depths. Change could be swift, while a reengineering a fleet is a glacial process unless something really, really bad transpires to compel the leadership to act swiftly and decisively. It takes time to transform ideas into widgets, and to develop sound tactics for employing them.

Next, with regard to fleet design, it may be instructive to think beyond the aircraft carrier as an analogy for this coming brand of subsurface warfare. Sure, the carrier air wing makes a nifty model for thinking about the functions of UUV flotillas. They would constitute the SSN’s long striking arm, much as fighter/attack jets comprise the flattop’s offensive punch. There’s value in mining this comparison. But the fit isn’t precise, is it? Presumably sub-force leaders have no plans to divest attack boats of their torpedoes and missiles, as naval aviation long ago stripped carriers of any serious offensive weaponry. They will retain battle power.

Subs, then, will be both vulnerable and heavy-hitting. There’s precedent for this quandary. A century ago naval historian Julian S. Corbett professed bafflement at the spectacle of hulking, thickly armored, heavily gunned battlewagons surrounding themselves with escorts to fend off torpedo-armed small craft like … submarines! For Corbett this constituted a “revolution beyond all previous experience.” The “old practice” was no longer a trustworthy guide. History furnished little help with foreseeing how sea combat might evolve.

Let’s not confine our quest for analogies to the deep, though, or even to the sea. In one sense the silent service is an undersea counterpart to the U.S. Air Force. Sound farfetched? Think about it. Subs rely on passive defense measures such as quieting to conceal their whereabouts. The latest air-force planes, such as F-22 and F-35 fighters, rely on built-in stealth to help them evade detection. Naval aviation trusts less to stealth than to active countermeasures such as electronic warfare to help airmen ride out enemy air defenses. Naval airmen defeat or fool defenses rather than elude them. Submariners might study the two paradigms—passive and active defense—to learn whatever lessons from the aerial domain are worth learning.

And as long as we’re bruiting about air power, is the SSN more akin to a fighter aircraft or to a bomber? There’s a division of labor that merits pondering. Fighters scour contested airspace of hostile forces, helping the bomber get through to its target relatively unmolested. Is the submarine a “fighter” in that sense? Or are UUVs the sub’s fighter squadrons, clearing out anti-access defenses so the sub—the “bomber”—can close the range to launch torpedoes or missiles? The question warrants investigating.

And lastly, as we gaze through a glass darkly into the future, Clark’s revolution could complicate—or foreclose altogether—certain strategic options involving submarines. It’s worth thinking ahead about those even as we obsess over hardware and tactics.

To name one, Corbett urged navies to concentrate assets at “focal areas” where shipping had to converge to pass from point A to point B. The sea may be tantamount to a wide, featureless plain, that is, but nautical passageways like the Strait of Malacca funnel shipping into narrow—and easily monitored—lanes. Subs are uniquely suited to loiter unseen off such narrow seas, watching—and potentially interrupting—traffic that passes through.

But what if they’re no longer unseen? If the sub and its human crew must keep their distance to avoid anti-access defenses, will UUVs—robots without human intuition and powers of observation—provide an adequate substitute? If not, strategies like “archipelagic defense” in Asia could underperform. If subs and their robot fleets can’t close narrow seaways to surface and subsurface traffic, the outlook for strategies premised on controlling them could prove dim. Thinking ahead about workarounds is imperative.