Not that either side needs a reminder of who’s who. The Chunxiao gas fields in the center of the East China Sea–where Beijing is hunting for energy in waters hard against the boundary line of the Exclusive Economic Zone (EEZ) claimed by Japan–are a long way from the back rooms of Tokyo. But there’s no question that events in this lonely corner of the ocean will be much on the mind of Shinzo Abe, Japan’s prospective prime minister, as he settles into his new job over the next few weeks. Earlier this month, tensions in the area rose another notch, when the Japanese government protested the completion of yet another Chinese drilling rig in the area. Tokyo fears that the Chinese might siphon off energy resources from its side of the line.

This isn’t just a scuffle over scarce natural resources, but one part of a much larger jigsaw puzzle of problems. The dispute over EEZ boundaries, for example, is intimately linked to China’s insistence that the nearby, uninhabited Senkaku Islands (Diaoyutai in Chinese) really belong to the mainland. Tokyo begs to differ. And behind the complex tussles over maritime law looms the much more fundamental issue of how to manage potential conflict between the rising naval aspirations of Beijing and the tightly linked forces of Japan and its ally the United States.

“Just look at the map,” says Toshi Yoshihara, an expert on naval strategy at the Naval War College in Newport, Rhode Island. To the north, he points out, the East China Sea gives way to the Tsushima Strait, one of the strategic linchpins of Northeast Asia, where Russia and Japan fought an epochal battle in 1905. To the south lies Taiwan, which Beijing has pledged to reunite with the People’s Republic, and which both Japan and the United States have recently begun to define as a common strategic interest they are obliged to defend. China’s rapid naval buildup– featuring a shopping spree in Russia for state-of-the-art weaponry, including superquiet Kilo subs–is aimed at helping it grab military control over Taiwan in the event of war. Part of its plan, say experts, involves pushing Chinese sea-defense lines far out into the western Pacific. But Beijing won’t be able to do that unless it can slip its subs and ships through the chain of the Ryukyu Islands, which extends Japanese territory nearly all the way to Taiwan (particularly if you include the Senkakus). The key there is Okinawa, home to America’s main military base in the region and the last bead in the Ryukyu chain.

For strategic purposes, China is trying to map the entire region’s sea bottom–and testing the reaction times and capabilities of Japanese and U.S. forces in the area. At the beginning of this year, for example, the Japan Defense Agency revealed that it had scrambled fighter jets 107 times last year in response to Chinese planes that were approaching Japanese airspace. The number in 2004 was 13; the year before that, two. In November 2004, a Chinese submarine actually entered Japanese territorial waters, threading its way through a gap in the Ryukyus. It was pursued by Japanese Navy planes until it left the area. Last fall, just as Japan was preparing for its general election, a group of Chinese warships turned up near the Chunxiao fields in a show of strength. One of the ships even aimed a gun at a Japanese surveillance plane flying nearby. “They were trying to send a message,” says retired U.S. Navy Rear Adm. Eric McVadon, a former military attaché in Beijing. “They were saying to the Japanese, ‘We used to be inferior to you. Now we have to be taken seriously’.” He notes that the main ship in the group was a high-tech destroyer purchased by the Chinese Navy from the Russians, who designed it, says McVadon, to counter U.S. Navy ships equipped with the powerful Aegis radar system.

As a potential flashpoint, the territorial dispute in the East China Sea is much more worrisome than the customary Sino-Japanese squabble over memories of World War II. As both nations maneuver for position, the threat of an accident, misunderstanding or fateful encounter that could draw the two sides into open conflict is rising. In July 2004, a Chinese naval vessel “came close” to a Japanese research ship, according to MSDF officials–close enough, other sources say, that the Japanese ship was forced to veer out of the way. “People play chicken,” says McVadon. “And that’s when things can happen.” The risk is compounded by the paucity of direct military-to-military contacts between the two sides.

There is one positive sign: both countries recently started talks about opening a “hot line” that could help smooth over potential incidents. But until that connection is made, and until the two countries establish more regular diplomatic contact and perhaps seek arbitration of the maritime EEZ disputes, the East China Sea will not be anywhere near as placid as it looks from the air.