Who cares about volcanic specks in Pacific? China, Vietnam, Japan.

A handful of volcanic specks in the Pacific Ocean are sparking fresh diplomatic ruckus, as China and its neighbors tussle over the resource-rich and militarily strategic seas that lie off their coasts.

Beijing infuriated Vietnam last week by announcing plans for a luxury tourist resort in the Paracels, a scattering of coral-fringed islets in the South China Sea that China, Vietnam, and Taiwan all claim as their territory.

Japan's plans for a port on its farthest-flung possession, the remote Pacific atoll of Okinotori, meanwhile, drew a sharp response from the Chinese Foreign Ministry, which accused Tokyo of violating international maritime law.

At the heart of both disputes lie the prospect of oil and gas wealth beneath the crystalline waters – and Chinese military ambitions.

The Paracels, lying almost equidistant between China and Vietnam, have been under Beijing’s control since Chinese forces seized the islands after a brief war in 1974. Since then, they have been mostly off-limits to civilians, and house only a military presence.

A tourist development plan released last week, however, foresees a high-end resort. Vietnamese Foreign Ministry spokeswoman Nguyen Phuong Nga demanded Monday that China abandon the project, which she said “causes tension and further complicates the situation.”

Ms. Nga’s Chinese counterpart, Jiang Yu, retorted Tuesday that Beijing has “indisputable sovereignty” over the islands. Whoever enjoys sovereignty also enjoys exclusive economic rights for 230 miles in all directions from the islands, over an area believed to hold rich oil and gas reserves.

Ms. Jiang had more to say on the subject of little-known Pacific atolls Thursday, when she charged that reported Japanese plans to build a port on Okinotori, which lies 1,050 miles south of Tokyo, “do not conform with international maritime law.”

How do you define 'rock'?

She was careful not to describe Okinotori as an island, however, nor even as an islet, an atoll, or a reef, since China calls it a rock.

The distinction is subtle but legally crucial. Under the 1982 Law of the Sea, “rocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone.”

China appears to want access to the area near Okinotori so that its submarines can map the seabed there, in readiness for any conflict over Taiwan, which Beijing claims as its own. Okinotori lies on the route US warships would take from Guam to Taiwan if they were called on to defend the island. The 160,000 square miles of ocean that Japan claims is also thought to be rich in minerals.

Japan has gone to great lengths over the past two decades to protect Okinotori from erosion and keep it above water, surrounding the tiny reef with wavebreakers filled with concrete. Aside from an observation platform on stilts, housing a meteorological station, only three lumps of rock protrude from the sea at high tide; they have all been reinforced with concrete, and one has been given a titanium shield to protect it from damage by wave-borne debris.

Japanese experts have also gone to great intellectual lengths to defend Tokyo’s right to extend an Exclusive Economic Zone from Okinotori, arguing that there is no definition of “rock” in international law.

The port for which the Japanese Transport Ministry has reportedly requested an initial $7 million would strengthen Tokyo’s claim to an EEZ by furnishing Okinotori with the “economic life” and “human habitation” that the Law of the Sea demands of a legally constituted island.