Andrew Krepinevich has an important essay in the March/April issue of Foreign Affairs. The article constitutes his brief for “archipelagic defense” in Asia. Krepinevich is the grand wizard of the Washington, DC-based Center for Strategic and Budgetary Assessments and author of the standard work on the U.S. Army in Vietnam. He espouses emplacing missile-armed troops along Asia’s “first island chain” as a deterrent. Anti-ship and anti-air units acting in concert with surface, submarine, and air forces could bar passage through the narrow seas that separate the islands.

Or, more accurately, fortifying the islands would threaten to confine shipping and aircraft within the China seas. Krepinevich aims that threat squarely at China. If Beijing believes it, the leadership may refrain from future misadventures at fellow Asian powers’ expense. That’s a congenial thesis. Indeed, my longtime wingman Toshi Yoshihara and I have been pitching similar ideas for some years now, both together and separately. Always good to welcome a new ally.

Archipelagic defense turns Asia’s nautical geography to advantage. Geography isn’t as forbidding for China as it was for, say, Imperial Germany. Fin de siècle Germany was an upstart empire whose leadership entertained grandiose naval ambitions. Unfortunately for Kaiser Wilhelm and his henchmen, their major seaborne rival, Great Britain, lay athwart the German Navy’s access to the open ocean. That made it a simple matter for Britain’s Royal Navy to bottle up its chief rival. And indeed, during World War I the Royal Navy mounted a “distant blockade” that made the North Sea into a dead sea imprisoning the German surface fleet. Afterward a German sea officer with a sharp pen quipped that his navy may as well have ruled the—landlocked—Caspian Sea!

Now, Asia’s offshore island chain is far more permeable than the British Isles. Beijing’s geostrategic dilemma pales by comparison with Berlin’s. Still, the islands enclose China’s entire shoreline, arcing southward from the Japanese home islands through the Ryukyus (including Okinawa, home to U.S.-Japanese forces), Taiwan, and the Philippines. Depending on how you construe this geographic feature, it meanders around the South China Sea rim, passing through the Indonesian archipelago before terminating at the Malacca Strait, East Asians’ most convenient entryway into the Indian Ocean. Or, the U.S. Defense Department’s annual reports on Chinese military power portray it as looping northward to terminate off central Vietnam.

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Some Chinese cartographers do just the opposite—tracing the island chain into the Indian Ocean and designating Diego Garcia as its western terminus. Such visuals concentrate minds, implying that a hostile alliance may rig a barricade all around China’s periphery. And indeed, such a doomsday prospect is increasingly thinkable. Naval technology has come a long way since Britain and Germany squared off in the North Sea. As Krepinevich observes, island defenders could deploy precision-guided missiles, sea mines, and an array of other weaponry—land-based implements of sea power—along the island chain.

The product: a thicket of defenses that People’s Liberation Army (PLA) ships and aircraft would be hard-pressed to breach. Why make such an effort? Demonstrating the capability to make the island chain impassable would put Beijing on notice that it will pay a heavy penalty for grabbing territory and subverting the Asian order. Severing sea routes connecting China’s economy with overseas markets or natural-resource suppliers would exact a fearful toll. Cutting PLA forces off from overseas theaters would hobble China’s foreign policy. Compressing north-south movement into narrow lanes along the Asian seaboard would expose seagoing traffic to disruption or destruction virtually within sight of home.

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An island cordon, then, is a Bad Thing from China’s standpoint. It would let the allies threaten to retaliate asymmetrically for, say, an assault on Taiwan, or to deny Beijing the access it craves to seas and skies beyond the island chain. If China believes the threat, it may desist from actions Washington and its allies want to discourage. That’s classic deterrence.