Diesel Submarines: The Game Changer the U.S. Navy Needs

September 23, 2018 Topic: Security Region: Asia Blog Brand: The Buzz Tags: SubmarinesMilitaryTechnologyWorldSSKSSNChinaJapan

Diesel Submarines: The Game Changer the U.S. Navy Needs

One of the world's best naval strategists presents all the reasons for acquiring diesel submarines to augment the existing nuclear fleet. And the navy needs to listen. 

Among the more-than-ample reasons for acquiring a flotilla of diesel-electric submarines for the U.S. Navy: SSKs could help deter war by demonstrating American resiliency should war come in the Western Pacific. Deterrence comes from capability and visible resolve to use it. And from staying power. Foes blanch at starting a fight if they fear they can do little to blunt an antagonist’s warmaking capability. In short, resilient contestants deter. And should war come anyway, an artfully employed diesel contingent could help the United States and its allies—principally Japan—prevail in that war.

To recap the case for conventionally powered submarines : SSKs could comprise the nucleus of an allied fleet. Procuring a common platform with the Japan Maritime Self-Defense Force (JMSDF), constituting a combined silent service, and stationing that fleet permanently in the theater would show that America has skin in the game of defending Japan. Tokyo would draw confidence from such a fleet. The alliance would emerge refortified.

In other words, Tokyo need not fear being left in the lurch if American sailors stand shoulder-to-shoulder with their Japanese brethren—and if the Japanese state and society know for a fact the United States will always be there during a rumble in the Pacific. It’s hard to overstate the value to Washington of keeping faith with allies and friends. America has no strategic position in Asia without bases on Asian soil. Merging part of the U.S. Navy into a genuinely multinational fleet would make a powerful statement about multinational solidarity—and help guarantee access to those bases.

Moreover, these are the right subs for the strategic environment. That’s doubly so if allied maritime strategy aims at bottling up Chinese or Russian shipping within the first island chain— as it should . It’s commonplace for nuclear proponents to claim that diesel boats are unfit for the job of closing straits and narrow seas to surface and subsurface traffic. For proof they run through the laundry list of advantages SSNs boast over their diesel-driven cousins—advantages such as their ability to stay underwater for indefinite stretches and cruise at high velocity. Case closed.

Well, no. SSKs have no need to match SSNs; they need to be good enough for the job, and cheap enough to buy in bulk. In effect champions of nuclear submarines deny that diesel boats can do what they have done for many decades. The U.S. Navy Pacific Fleet sub force tormented the Imperial Japanese Navy during World War II, including along the island chain. Undersea warfare could have proved decisive in that conflict. The JMSDF unleashed similar tactics vis-à-vis Soviet and Chinese shipping during the Cold War. Both navies prosecuted an island-chain strategy to good effect, and with more rudimentary diesel boats than today’s to boot. Denying historical fact doesn’t add up to a terribly convincing case against SSKs.


An allied sub squadron wouldn’t need SSNs with breakneck speed and unlimited underwater endurance to defend a static island perimeter. SSNs excel at open-ocean combat, but they represent excess capacity and expense—and thus waste—for sentry duty. A U.S.-Japanese squadron would need subs to man the barricade in concert with surface craft, missile-armed troops on the islands, aircraft roving overhead, and well-placed minefields. Picket subs thus need to hover silently and stealthily along the island chain, awaiting their chance to strike.

Diesels can do that. The alliance needs enough sentries to keep up a constant rotation, assuring enough subs are always on guard, along with a reserve to shore up the line when vessels are lost in action. A U.S.-Japanese sub fleet would boast enough hulls to keep up a rotation along the Ryukyus. The JMSDF gets by with nineteen boats after a modest buildup, but the leadership wants more. Add a dozen or so American boats to the combined order of battle, and you’d have an undersea fleet able to hold the line with enough units to spare for offensive missions such as raiding shipping within the Yellow or East China Sea or the Sea of Okhotsk.

So this is the right force for the times, and it can be had at a low, low price compared to an SSN contingent. Affordability translates into mass for the fleet. The more boats the better. It appears that the price of the latest Japanese-built Soryu diesel boat is one-fifth that of the latest American Virginia-class SSN ( $631 million v. $3.2 billion ), but let’s assume you get four hulls for the price of one after the navy and Congress muck around with the program. That suggests the navy could outfit a twelve-boat squadron for the cost of three Virginias.

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