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China unilaterally outlined a new air defense zone, drawing the ire of the U.S., Japan and South Korea last week. Now the Koreans wants to redesign their air defense zone, too, escalating rather than easing the fight over these invisible, made-up borders.

The Diplomat can help us catch up:

According to a number of local reports, ROK National Security Office chief Kim Jang-soo convened a meeting of top South Korean security officials on Sunday to discuss the new [air defense zone].

The Korean Herald reported that the [air defense zone] is rumored to include the “country’s southernmost island of Marado; Hongdo Island, an uninhabited island south of Geojedo Island; and Ieodo, a submerged rock within the overlapping exclusive economic zones of South Korea and China.”

This is South Korea's most direct challenge against China — claiming ownership of a long-disputed submerged rock — since this global brinksmanship drama began.

Last weekend, China unilaterally established an air defense zone to cover space over the East China Sea (that overlaps with a disputed grouping of islands claimed by Japan and South Korea), demanding that other countries file flight plans with Chinese officials before entering the zone's boundaries. China warned of "emergency defensive measures" if countries refused to comply. Testing that theory, the U.S. ran two B-52 bombers through the zone on Wednesday for a "long-planned" training exercise. Nothing happened, but complaints were raised.

The exercise was seen as direct rebuke to China's unilateral action in support of Japan and South Korea, U.S. allies in the region. Following suit, Japan and South Korea flew planes through the region without incident. Japan ordered commercial carriers to ignore the new defense zone.

But the issue ramped up again Friday when China claimed to scramble fighter jets to the new air defense zone to investigate any further U.S. or Japanese activity. Over the weekend, the Federal Aviation Administration instructed American commercial flights to comply with China's new policy, which didn't please the Japanese. Drastic measures are being taken to avoid offending anyone, but in the complicated politics of East Asia, not offending one party often means slighting someone else. 

On the other hand, the administration doesn't want any danger coming to a U.S. commercial flight, as The Wall Street Journal explains:

U.S. carriers, caught between diplomatic pressures and safety considerations, are seeking a way to avoid further ratcheting up tensions, said a person familiar with the U.S. position. With the apparent blessing of the U.S., this person said, they are filing flight plans with both Japan and China. At the same time, affected routes are being modified to avoid disputed airspace as much as practicable.

A B-52 can defend itself. A jet filled with civilians can't, and the U.S. would rather not improve or damage its relationships with China and Japan.

This mess aligns swimmingly with Joe Biden's planned trip to the region, where he has meetings booked with Chinese, Japanese and Korean leaders. "He will hold talks with leaders of all three nations and on Friday pay a visit to the demilitarised zone which divides the two Koreas," the BBC notes of his trip. "But the air zone row is likely to dominate the week."

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