I am more sanguine than most about how the Japanese Self-Defense Forces stack up against China’s People’s Liberation Army. The SDF would acquit itself well in combat if commanders artfully combined all warfighting implements at their disposal, from ships to aircraft to shore-fired missiles. Tokyo has options; it even has advantages.

Judging from the contents of my email inbox the past few weeks, however, some Japanese commentators mistook this guardedly upbeat assessment for a prediction that Japan would prevail in any trial of arms—including a clash over the Senkaku/Diaoyu archipelago, west of the southernmost tip of the Ryukyus chain. Au contraire. Extolling the JSDF’s material and human excellence in general terms is a far cry from predicting a Japanese triumph in any particular contingency. There are no sure things in war.

Furthermore, a Senkakus conflict is probably the hardest case the JSDF may confront. Glance at the map. Geography may not be destiny, but it molds destiny. The archipelago lies within easy reach of PLA air, naval, and missile forces concentrated opposite nearby Taiwan. Advantage: China. On the allied side, Okinawa is home to U.S. Marine and Air Force bases as well as the JSDF’s Naha Air Base. It is situated a couple of hundred miles away, roughly the same distance as the mainland coast. That’s no small thing. But the Senkakus are remote from major bases in the Japanese home islands. The U.S. naval station at Yokosuka, for example, lies over 1,000 miles distant.

Even though Japan holds the contested ground, then, geography and the balance of forces would favor China should a conflict transpire today. The PLA will hold that edge unless Japan takes dramatic measures to fortify its southern ramparts. If the JSDF cannot win the air and sea battle around the Senkakus, it will lose the islands to any concerted PLA offensive. If nothing else, Chinese forces that controlled nearby waters and airspace could simply cordon off the archipelago and wait out the JSDF. Any Japanese defenders emplaced there would wither over time, bereft of food, water, and other critical supplies.

What to do? If commanding the air and sea is the key, then Tokyo must devise forces and plans for assuring JSDF access to the islands while denying PLA forces access. That could mean positioning mobile anti-ship missiles on Yonaguni Island, at the southern tip of the Ryukyus and within missile range of the Senkakus. (Such a move would be certain to play well with the locals.) It could mean expanding the submarine fleet and adjusting submarine deployment patterns southward. Patrolling the waters near the islets would comprise a potent deterrent. It could mean fielding new classes of small missile craft to wage guerrilla war at sea against Chinese surface ships—much as the PLA Navy envisions doing against U.S.-Japanese naval forces.

It certainly means Tokyo must act. Agonizing endlessly over measures like stationing token ground forces in the Ryukyus—as the nation has been doing for years now—does little to shore up Japan’s strategic position along its southern periphery. Fielding excellent military forces is a start. But if Japan’s leadership wants to win, it must put the JSDF in position to do so. Faster, please.