Benefits of SSKs for US, Soryus and Collins mentioned

The submarine campaign grew more and more effective as the U.S. offensives undulated across the Central and South Pacific. U.S. Navy, Marine and Army amphibious forces wrested outer islands from Japan, letting the navy position, maintenance and logistics outposts closer to the foe. Submarine tenders—floating repair and supply depots for all intents and purposes—staged support operations westward of Hawaii. As the transpacific campaigns progressed, boats wasted less time transiting to and from assigned hunting grounds. They spent more time strewing the seafloor with enemy merchantmen and men-of-war.

Forward bases, then, offset the tyranny of distance—allowing the submarine force to mount a stifling presence in Asian waters. Wartime prime minister General Hideki Tōjō catalogued submarine warfare among three critical determinants of Japan's defeat—high praise from someone in a position to know.

And afterward? Ravaged by undersea combat during World War II, Japan built an impressive submarine force of its own to help prosecute the Cold War. Japan Maritime Self-Defense Force (JMSDF) diesel boats turned geography to advantage, lurking in and around the straits that pierce Asia's offshore island chains. Crews monitored and encumbered east-west movement between the China seas and the Western Pacific. Soviet skippers often balked at attempting the passage. The JMSDF, in short, forged itself into a lethal weapon for a cold war beneath the waves.

And so it remains. JMSDF Soryu-class diesel attack boats are the biggest boats of their type, and they're acclaimed among the best—for good reason. Their size lets them carry large amounts of fuel, weaponry and stores, making long patrols feasible. The depths offer a sub its best concealment. Accordingly, Japanese SSKs are outfitted with air-independent propulsion, obviating their need to surface and snorkel frequently. That's an Achilles' heel of older diesel subs. Soryus, then, can remain underwater for long stretches, evading detection from the surface or aloft. And their acoustic properties are excellent while submerged—helping them elude enemy passive sonar. What adversary sonar men can't hear can hurt them.

In short, Soryus are optimized for plying the China seas and Western Pacific. Those are precisely the waters the U.S. Navy, Marine Corps, and Coast Guard singled out as crucial in the 2007 Maritime Strategy, the sea services' most authoritative statement of how they see the strategic environment and intend to manage it. Soryu SSKs are proven platforms manned by experienced mariners who can bequeath their knowledge to their U.S. comrades. That makes these boats a logical common platform around which to build a combined SSK squadron.

Let's evaluate the Soryus' candidacy while remaining mindful that many other capable diesel subs—for instance, the German Type 214—are also on the market and worth considering. In operational terms, what would a U.S.-Japanese force do? Its strategic rationale would be straightforward: it would turn access denial against China, its foremost contemporary practitioner. Reciprocity is a fine thing. Or, if you prefer your strategic wisdom colloquial, paybacks are a b*tch.

In other words, if Beijing wants to deny U.S. forces access to the theater, U.S. and Japanese commanders should reply in kind. They can deploy submarines along the first island chain to fight in concert with surface forces, detachments of missile-armed land troops, and shore-based tactical aircraft. Combined-arms forces could:

-     Keep the People's Liberation Army (PLA) from wresting away beachheads in the island chain. Bursting through the island chain would turn Japan's southern flank (and Taiwan's northern flank), compromising Japanese territory while making it far harder to cordon off the China seas. Defending the islands should be Job One for allied forces.

-     Expel China's flag from crucial seaways. Plugging, say, Miyako Strait (south of Okinawa) with submarines while erecting overlapping fields of anti-ship-missile fire overhead would give the most determined PLA Navy skipper pause. He would think twice before trying to exit the East China Sea for the Western Pacific (or to return to home waters if caught outside).

-     Make transiting north-south along the Asian seaboard perilous in the extreme. SSKs venturing within the island chain could target merchantmen and PLA Navy units with impunity, imposing unbearable costs on Beijing for making trouble.

In short, staging a combined fleet near likely scenes of action would give rise to a kind of mutual assured sea denial. Properly executed, allied anti-access preparations would yield a measure of deterrence vis-á-vis China—enhancing prospects for uneasy peace in the Far East.

But why diesel boats? Isn't the all-nuclear U.S. silent service the world's finest, a silver bullet in the navy's chamber? Yes and no. A U.S. Navy boat remains the odds-on favorite in a duel against any single antagonist. Mass is a severe and worsening problem, however. If the fleet disperses itself all over the map, as global navies are wont to do, it's apt to find itself outmatched at some trouble spot or another. Never mind how capable an individual platform may be. If commanders concentrate assets in one trouble spot, on the other hand, other priorities may go uncovered. Now as ever, quantity has a quality all its own. And quantity is precisely where trouble lies.

The reason for dwindling fleet totals should astound no one. It's dollars and cents. As Cold War-era Los Angeles-class nuclear attack subs (SSNs) retire, they're being replaced not on a one-for-one basis but by fewer, more expensiveVirginia-class SSNs. As costs rise and shipbuilding budgets stagnate—if that—downward pressure on numbers mounts inexorably. The fleet is projected to sag from 55 SSNs today to as low as 42 around 2030.

Forty-two sounds like a lot, doesn't it? But naval leaders are forever reminding us that seven-tenths of the earth's surface is covered by water. The seven seas adds up to an awful lot of waterspace for 42 boats to police—especially since a sizable fraction of that tally is in overhaul, routine maintenance, or workups on any given day. Many units, that is, are unavailable for combat duty no matter how sorely they're needed. Shave a third off the raw number of ships and you have a good guesstimate about the number of subs available to some degree or another.

Sure, 60 percent of the SSN contingent now calls the Pacific home. But though the percentage sounds impressive, that's only 33 vessels, a number that could shrink as low as 25 by 2030. And allied fleets? The JMSDF is expanding its own subsurface contingent from 16 to 22 SSKs, mainly by extending the service lives of boats already in the inventory. Thus a combined U.S.-Japanese fleet of 47 subs would be arrayed against some 70 PLA Navy attack boats within the foreseeable future. But even that figure probably exaggerates. It relies on the doubtful assumption that Washington concentrates the entire Pacific Fleet submarine force in the Western Pacific—letting commitments elsewhere go.

That's a 50 percent advantage numerical advantage for China—at a minimum. Again, allied submarines remain superior, boat for boat, but at some point brute numbers begin to tell. So the challenge before Washington is to add capable boats to its fleet on the cheap. (Tokyo could do its part by scrapping its self-imposed cap on defense spending and investing more generously in undersea warfare.) Here the figures are striking. The unit cost for the Soryu is estimated at $500 million, whereas each copy of the Virginia class comes in at a cool $2.8 billion. Do the math. It appears the U.S. Navy could afford five Soryus for the price of one Virginia, with change left over. That's bang for the buck.

Admittedly, the barriers to reentry into conventional submarine warfare would be formidable. For one, the ghost of Hyman Rickover would haunt any such debate. SSKs, unlike SSNs, command little obvious constituency within the submarine force, the navy, or Congress. Overcoming the all-nuclear mystique would demand concerted effort on the part of diesel proponents, perhaps with help from some truly dire budgetary pain. Such pain is more likely than not. In the 2020s, for instance, the navy will commence replacing its Ohio-class ballistic-missile submarines. Top navy leaders have warned that this project alone could drain shipbuilding coffers. Inexpensive non-nuclear alternatives may come to look palatable—if not downright appealing—under such fiscal circumstances.

Next, cultural proclivities aside, the nuclear navy would likely construe any move to acquire diesel boats as a threat to current SSN procurement plans. They might see an SSK program as a substitute for new Virginias, not as a complement to the nuclear-powered fleet. It would look like an attempt by cost-cutters to save money on the sly, at the expense of operational effectiveness. Defense manufacturers—particularly those specializing in naval nuclear propulsion—would add their voices to the din. And the outcry would be universal and twice as loud should Washington contemplate buying foreign—witness the uproar among Australian firms over Canberra's apparent decision to buy Soryus rather than replace its Collins-class SSKs with an indigenous make.

In short, the pushback from guardians of the status quo would be frightful to behold. This is a debate worth having nonetheless. Think about the upsides to diesel subs, even apart from their modest cost:

-     If indeed the Australian government proceeds with a purchase of ten Soryu-class boats to replace its underperforming Collins class, the Soryu could form the nucleus of a multinational East Asian submarine force spanning more than just the U.S. Navy and the JMSDF. Other partners could join in. Basing, maintaining, and employing a standardized fleet would be far easier than it is with the usual hodgepodge of ships built by many designers from many countries.

-     Multinational detachments could operate not just from Japan or Guam to the north but from the Philippines or Australia to the south. A standing allied presence along the first island chain would constitute a potent deterrent to Chinese mischief. So would an exterior position in Australia. Such a strategic position would grant diesel boats access to the South China Sea at many points along that expanse's permeable rim.

-     As World War II and the Cold War proved, proximity to patrol grounds magnifies the operational and strategic efficacy of undersea combat. Short transit times equates to more time on station and less wear-and-tear on people and hardware. Mounting patrols from homeports in the region thus boosts the number of hulls ready for sea when the balloon goes up.

-     Embracing a time-tested common platform would ease the interoperability problems that plague multinational ventures. Dissimilar gadgetry, tactics, techniques, and procedures, and national and service cultures throw sand in the gears of coalition operations, generating the "friction" that Carl von Clausewitz bewailed two centuries ago. The lubricant Clausewitz recommended was combat experience. Yes; and combat experience lubricates best when the warriors all carry the same arms. Never underestimate the power of standardized equipment—especially when a corps of experts, namely JMSDF submariners, already exists that can pass down knowledge and expertise to newcomers. U.S. submariners could ascend the diesel-boat learning curve swiftly, making themselves proficient in this new, old technology.

-     And lastly, a return to conventionally powered subs would confer side benefits within the U.S. Navy. Since the inception of atomic power, with its technical rigor and time-consuming training, it has become rare indeed for surface-ship sailors to cross over to serve in submarines, or vice versa. It's almost unheard of to do what, say, a guy named Chester Nimitz did: start off life as a submariner before going on to serve in cruisers. Reintroducing conventional subs could reintroduce the professional mobility of times gone by. Each community would profit from knowing the other's operating element firsthand. The navy as a whole would profit from collapsing some of the stovepipes—a.k.a. "cylinders of excellence"—that separate communities from one another to such baneful effect.