DIESEL SUBMARINES: The Game Changer the U.S. Navy Needs.

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.

This is all true. Manning up a large number of new subs might prove to be a problem, however.