A few years ago I had the pleasure of hoisting a pint with Rear Admiral Sumihiko Kawamura, a retired commander of the Japan Maritime Self-Defense Force’s anti-submarine air force. Yesterday Japan Times published an interview with Admiral Kawamura in which he opined that Beijing sees the Senkaku/Diaoyu Islands as the northern sentinel guarding a submarine “bastion,” or safe haven, in the South China Sea.

This would be a reprise of how the Soviet Navy worked around Far Eastern geography and U.S.-Japanese naval strategy during the Cold War. JMSDF mariners raised anti-submarine warfare to a high art during the protracted East-West standoff. Japanese boats and aircraft kept watch over the narrow seas through which Soviet nuclear-powered ballistic-missile submarines had to pass to reach the broad Pacific. The Kurile straits were favorite JMSDF hunting grounds. Allied ASW assets held Soviet SSBNs at risk whenever they sought to exit the Sea of Okhotsk or other enclosed expanses. Many Soviet skippers chose not to bother. Instead they conducted deterrent patrols within those relatively confined waters, taking advantage of the increasing range and lethality of sea-launched ballistic missiles.

Kawamura argues, in effect, that People’s Liberation Army Navy SSBNs, like their Soviet predecessors, cannot elude detection while passing through the first island chain en route to Pacific patrol grounds. Quieting technologies—silent-running propellers, shock mounting for machinery, hull coatings, and the like—remain too immature for effective concealment. “When navigating,” as he puts it, “Chinese submarines sound like they are pounding a drum or bell.” (An old U.S. Navy joke holds that noisy subs sound like two skeletons, ahem, having carnal knowledge of each other inside a metal garbage can.) The PLA Navy undersea fleet, then, must shelter within the island chain until it corrects these deficiencies and improves its own ASW capacity—bolstering its ability to penetrate or evade allied defenses.

I have no quarrel with the idea that Chinese SSBNs will roam the South China Sea in the coming decades. The submarine base at Sanya, on Hainan Island, is convincing evidence of that. Three points, though. One, the South China Sea may be more than a bastion. It may be an outlet to the Pacific Ocean via the Luzon Strait, which separates the southern tip of Taiwan from the northern Philippines. Stationing SSBNs well to the south allows the PLA Navy to stretch allied ASW defenses. Short of operating from Taiwan or the Philippines—neither a realistic prospect—JMSDF and U.S. Navy ASW forces will find it hard to continuously monitor the strait. That improves Chinese commanders’ chances of slipping into the open sea—as they must until weapons engineers extend the range of PLA Navy SLBMs sufficiently to hold the American mainland at risk from Southeast Asia. Admiral Kawamura may be overselling allied fleets’ capacity to impose blanket coverage along the island chain.

Two, there are good reasons apart from technology for Beijing to keep the fleet closer to home. Western navies are remarkably easygoing about letting captains vanish beneath the waves for weeks on end, taking doomsday weapons with them. Authoritarian regimes like the Soviet Union and Communist China fret about political reliability. As Kawamura predicts, the PLA Navy undersea fleet may operate from the South China Sea, or even from the Bohai Sea, at Beijing’s nautical door, once missile technology permits. But political reasons could account for such relatively restrained deployment patterns. Chinese nuclear strategy need not be a rerun of Soviet strategy—despite the two communist powers’ similar offshore geography and kindred autocratic regimes.

And three, it’s unclear to me how occupying the Senkakus would significantly tighten Chinese ASW defenses in southern waters. Admiral Kawamura furnishes few details in Japan Times, so it’s hard to say what he has in mind. It is possible, I suppose, that the islets could supply the eastern terminus for a line of underwater hydrophones, helping PLA Navy ASW forces detect Japanese or American boats transiting north-south along the Asian seaboard. Such an arrangement would hark back to the far more extensive, deep-water SOSUS array NATO strung across the Greenland-Iceland-U.K. gap to impede Soviet access to the Atlantic. Or perhaps a PLA outpost in the Senkakus could guard against adversaries’ attempts to disrupt such a listening array. It’s worth remaining on the lookout for such developments.

For more on potential PLA Navy SSBN deployment patterns, have a look at an essay Toshi Yoshihara and I wrote a few years back.