Tensions escalated with the announcement by China's Ministry of Defense that it was establishing an Air Defense Identification Zone, or ADIZ, above the Senkaku/Diaoyu chain of islands in the East China Sea, essentially to justify Beijing's air force activities there. The ADIZ designation is something many nations have used in uncontested airspace to enhance air security since the early 1960s. It requires civilian aircraft to notify the ADIZ power upon entry. Challenges to the rules and angry rhetoric, particularly from Japan and the United States, immediately followed China's declaration.
Japan insisted it would not stop its own patrols in the airspace and forced its commercial airlines to disregard China's flight rule. China downplayed America's B-52 challenge with a response that the aircraft only neared the ADIZ and remained 200 kilometers from the disputed islands.
The skirmish reached a head on Nov. 29 when the People's Liberation Army Air Force confirmed it sent warplanes — including Su-30 and J-11 aircraft — along with a domestically designed KJ-2000 airborne early warning and control system into the disputed ADIZ. The warplanes reportedly spotted 10 flights consisting of Japanese E-767s, P-3s and F-15s and U.S. P-3s and EP-3s passing through the ADIZ.
Regardless of the immediate tit-for-tat, the events of the week serve as a reminder to Beijing of the strength of the U.S.-Japan security relationship. The quarrel also raises significant questions regarding China's ability to effectively enforce the ADIZ.
Overlapping Claims Above the High Seas
The zone, which falls on the eastern fringe of China's claimed exclusive economic zone, overlaps with Japan's own newly extended ADIZ, parts of the South Korean island of Jeju and Taiwan's ADIZ. Most important, the ADIZ covers areas of potentially rich natural gas fields that surround the Japanese-claimed Senkaku/Diaoyu Islands.
China's establishment of such zones has been slower than that of many countries, including the United States and China's regional rivals such as Japan and Vietnam. Japan established its own ADIZ in 1969 and has repeatedly extended its scope. Responding to China's growing military assertiveness, Japan in June unilaterally extended its ADIZ 22 kilometers westward, and now it lies 130 kilometers off the Chinese mainland at its closest point. This goes beyond the currently disputed area and overlaps with Taiwan's ADIZ. While China's new ADIZ has not gone beyond international norms, the fact that it overlaps with those of three other countries is perceived as a provocation.
An ADIZ is different than "airspace." As defined by international law, airspace comprises the sky above a territory plus 12 nautical miles (22 kilometers) of coastal waterway. By contrast, an ADIZ is a unilateral means for a country to identify and monitor aircraft approaching its territory and its more formally defined airspace.
In theory, an ADIZ does not constrain aerial passage as long as an aircraft gives advanced notice and follows all the rules. Violation, however, is seen as an incursion and can prompt a military response. Thus it gives a country a pre-emptive position and lends legitimacy to a scrambling of defensive aircraft before the violators actually penetrate national airspace. Japan has scrambled aircraft repeatedly since December 2012, when it extended its own ADIZ in response to an increase in the number of Chinese warplanes and drones active over the sensitive islands. In the third quarter of 2013 alone, Japanese military planes were scrambled 80 times in response to Chinese activity.
Thus the new Chinese ADIZ could be perceived as retaliation against Japan. Additionally, Beijing is testing U.S. responses in the Western Pacific, as China attempts to shape a new maritime balance in the area. All sides will use the current standoff to recalibrate the balance of power over energy and maritime geopolitics that, much like during the Cold War, is unlikely to lead to an outright clash. Still, the aerial competition amid overlapping claims does increase the likelihood of miscalculation or accident.
Rebalancing Air Defense
By establishing the new ADIZ, China also faces a significant challenge to its enforcement. An effective ADIZ requires two main capabilities. The first is the ability to monitor all of the desired airspace with sufficient scope. In a littoral environment subject to two or more competing ADIZs, this is best accomplished with a combination of ground-based, naval and airborne systems.
This reality gives a slight advantage to Japan, since it has multiple islands throughout the region with ground-based systems that can establish and efficiently monitor airspace more consistently than airborne platforms. The Chinese, meanwhile, are limited because the mainland ground-based systems used to cover the ADIZ are much farther away, increasing China's dependence on airborne early warning systems. China has multiple models of such systems in the early stages of production and use that have limited capability, but they are quickly gaining ground. Japan is further ahead technologically and doctrinally with this type of platform, which has been part of its military for decades.
The second prerequisite of an effective ADIZ is a country's ability and will to project force (and deal with the potential consequences). Ground, sea and air platforms can all be used to enforce airspace, but one cannot shoot or threaten to shoot something without being able to see it and without having the appropriate weapon within range. Military aircraft are routinely used to intercept transgressing aircraft and enforce the ADIZ, so it is important for an air force base to be close to the zone.
China is thought to have acquired and developed the assets required to accomplish all of the above, but it has yet to position them in a way that would cover all of its new ADIZ. China is more militarily competent near its mainland, but the farther out the ADIZ extends, the more constrained China becomes — and limited in terms of the tools at its disposal. This underscores China's need to develop specific procedures and training protocols and dedicate appropriate assets to effectively enforce its new ADIZ.
Shaping a New Status Quo
The growing aerial trend in the East China Sea disputes adds another dimension in the already tense seaborne competition over the Senkaku/Diaoyu Islands, following the Japanese government's nationalization of three islets in September 2012. Before then, the islands, although disputed by China, were only infrequently sources of direct tension between Japan and China, since the two sides had earlier come to a tacit agreement that China would not push its claims if Japan did not develop the islands.
This has now changed. While the nationalization did not alter the fact that Japan has no development on the island, it apparently prompted Beijing to shift from its previous pragmatic approach and embark on a nationalist campaign to redefine the boundary.
Against this backdrop, China has increased patrols by maritime surveillance and fishing vessels near the disputed waters, and this has precluded Japan from confronting China with naval vessels. In particular, as the vessels were dispatched well within Japan's 12 nautical miles of territorial waters around the islands, it underscored China's implicit claims of sovereignty. Beijing also announced the intention to demarcate its own territorial waters 12 nautical miles off the islands to further its claims. Added to this is China's increasingly hard-line approach over joint exploration in the natural gas fields in the East China Sea that has largely precluded Japan from participating.
In the near term, Beijing is aiming to shift the fact of Japan's de facto control over the disputed islands toward a new balance that recognizes China's emerging maritime interests and presence. As with similar maneuvers by Beijing in the South China Sea disputes, China understands that its attempt to establish a new balance in the maritime sphere is confined so long as it wants to avoid provoking a serious response from the United States.
Serious aggression over maritime boundaries with Japan could not only justify Japan's process of military normalization but ultimately bring U.S. military power into the equation, since Washington has repeatedly emphasized that it considers the area covered by U.S.-Japan security agreements. This would not be in China's interests, but Beijing nonetheless appeared to be willing to test the U.S. commitment and assert its claim not only to the islands but also to its enlarged sphere of influence. That said, such deliberate ratcheting up of tensions with tools like the ADIZ is forcing all players to readjust their behaviors in light of China's increasing regional ambitions and naval heft.