Foreign Policy Blogs

China’s ADIZ; or, What the Heck Is Going On in the East China Sea?

Diaoyu, or Senkaku? (Photo:

Diaoyu, or Senkaku? (Photo:

China sent the diplomatic world into a spin on November 23 by declaring an Air Defense Identification Zone (ADIZ) in the East China Sea. This is cause for some concern, given the state of Sino-Japanese relations. The concern has been boosted by some vague and rather provocative Chinese statements but also by the fact that most normal people, and many public officials, have no idea what an ADIZ is or what is being claimed.

To be clear, an ADIZ is not a claim of sovereignty over international waters, and it is certainly not a no-fly zone through which the aircraft of other nations are not allowed to travel. Yet the ambiguity of Chinese statements and the disputed claims of sovereignty over the Senkaku/Diaoyu Islands make the issue worth examining.

All countries enjoy sovereign rights in the airspace over their territory, including their territorial waters, which nowadays extend 12 nautical miles from the shore. ADIZs come into play in airspace beyond that. Under the U.S. definition, an ADIZ is a zone in which civil aircraft must identify themselves and may be subject to air traffic control if they intend to travel from international airspace into sovereign airspace. (Most regulation concerning nonsovereign airspace relates specifically to civil aviation, leaving the rules for military aircraft somewhat up in the air, as it were.)

There is no international law, however, that specifically regulates, or even defines, the ADIZ. The concept came from a unilateral U.S. declaration in the 1950s, when Washington determined that its security required the identification of high-speed aircraft before they reached territorial waters (3 nautical miles in those days). A score of other countries followed suit with similar unilateral declarations. In addition to defense, the U.S. government lists such purposes as: controlling illicit drug activities, minimizing unnecessary intercept and search-and-rescue operations, and reducing the risk of collisions or other hazards. The United States maintains five ADIZs—Atlantic Coast, Pacific Coast, Alaska, Hawaii, and Guam—extending 250–400 miles from the shore. The United States does not impose its regulations on foreign military aircraft transiting the ADIZ if they are not headed into U.S. sovereign airspace, and it does not inform foreign governments when its military aircraft similarly transit their ADIZs.

China’s new ADIZ overlaps three existing ADIZs in East China Sea, those of Japan, Taiwan, and South Korea. In fact, the Chinese made of point of noting that their ADIZ extends as far eastward as Japan’s extends westward. The overlap with Japan’s ADIZ, in particular, is considerable. That, in and of itself, does not have to be a problem. If worse comes to worse, aircraft can report their positions to both countries. The problem comes in that the ADIZ includes the disputed islands known in Japan as Senkaku and in China as Diaoyu. China cannot legally impose rules over the sovereign territory of another state, thus the ADIZ declaration is another way of expressing its denial of Japanese sovereignty over the islands.

Curiously, China’s ADIZ also includes Ieodo, a submerged reef claimed by South Korea. Although Ieodo did not lie within South Korea’s ADIZ, Seoul apparently takes the claim quite seriously. The curious part is that, strategically speaking, China has long benefited from the animosity between South Korea and Japan, the United States’ two key allies in the region, and it has seen its own relations with South Korea improve greatly over the last decade or so. Now, through its own actions, China has put the two of them on the same side of an issue. On December 8, South Korea responded by extending its own ADIZ, which now also includes Ieodo.

Apart from the fact of China’s ADIZ declaration, China needlessly heightened tensions with the way in which it carried it out. It was unclear as to whether the rules referred only to aircraft approaching undisputed Chinese airspace, as U.S. practice does, or if they obligated all aircraft transiting the zone regardless of direction or destination. Then Beijing warned that aircraft that failed to submit flight plans in advance, maintain radio contact with Chinese authorities, and follow the directions of the Chinese Ministry of Defense could face unspecified “emergency defensive measures.” That is a rather harsh stance toward an ADIZ in peacetime.

Initial responses to the Chinese declaration varied. Japan and South Korea instructed their civilian airlines not to comply with the new rules. The United States advised its airlines to comply for safety’s sake, but purposely flew Air Force B-52 bombers through the zone (not in the direction of Chinese airspace) without complying in order to demonstrate its rejection of China’s unilateral claim.

Up to this point, China had argued that it has sovereign rights over its maritime 200-nautical-mile exclusive economic zone (EEZ) and the air above it, a right that few other countries recognize. From this perspective, the assertion of an ADIZ could be considered an act of moderation, a move in the direction of more widely accepted international practice. Still, China’s ultimate intentions are unclear. Is it merely claiming the rights that other aspiring great powers have acquired? Or is it engaged, as some believe, in “salami tactics,” a series of steps designed to be insignificant and unthreatening when viewed in isolation but which change the underlying dynamics of the game in their accumulated effect?

China and the United States have both softened their positions since their initial statements. The United States seems to have shifted from insisting that the ADIZ be revoked (which is unlikely) and inquired as to how it might be implemented. China has clarified that it does not intend to shoot down aircraft that violate its rules or even to send fighters to monitor them unless they are deemed a threat. Nevertheless, the official U.S. position is still not to recognize the ADIZ, and military flights through it are unlikely to cease. Given the sovereignty issues over Senkaku/Diaoyu, Japan is unlikely to acquiesce. The situation will bear watching for some time to come.



Scott Monje

Scott C. Monje, Ph.D., is senior editor of the Encyclopedia Americana (Grolier Online) and author of The Central Intelligence Agency: A Documentary History. He has taught classes on international, comparative, and U.S. politics at Rutgers University, New York University (SCPS), and Purchase College, SUNY.