China’s ADIZ in the East China Sea

On 23 September 2013, China’s Ministry of National Defense announced the establishment and entry into force of the East China Sea Air Defense Identification Zone (ECS-ADIZ). Although there had been earlier official statements on China’s intention to regulate the nearby skies, the proclamation took the world by surprise, prompting a flurry of responses from countries both near and far. Most notably, the reaction from the United States and its close allies, Japan and South Korea, suggested that the already-strained regional security framework had entered into a new phase where the sides openly challenged and tested each other’s resolve. In this respect, the US showed perhaps the most potentially consequential reaction by sending two unarmed nuclear-capable bombers into the newly-announced ADIZ without informing the Chinese authorities. Similar US military patrols and training missions within the zone have continued unabated ever since.

Many comments and analyses have already been made on this issue; however, in many cases, these pieces have created greater confusion, largely due to the numerous ambiguities and conflicting reports surrounding the situation. This essay takes a step back and offers a critical overview of the recent developments. In doing so, it attempts to identify the major actors in the crisis and clarify their respective positions, concentrating particularly on the US reaction and strategy toward the Chinese ADIZ. It then undertakes a strategic analysis on the implications of China’s ADIZ from a regional security perspective.

ADIZ and International Law

Simply put, an ADIZ “is an area in airspace over land or water which may not be over the sovereign territory of a State in which ready identification, location and control of all aircraft is required in the interest of national security.” The rationale for the establishment of an ADIZ is to satisfy certain security concerns of a nation and enable it to maintain a more effective control over its peripheral airspace. An ADIZ allows a state to take precautionary (or preemptive) measures against threats, real or perceived.

An ADIZ can be analogous to a warning zone in which any aircraft that enters the prescribed zone is identified and monitored. In this respect, it is neither a no-flight zone nor an extension of a state’s sovereign airspace. Essentially, an ADIZ still constitutes international airspace and it is not a binding agreement recognised by international law. Hence, from a legal perspective, it neither reinforces nor impinges on claims of sovereignty. Furthermore, an ADIZ does not restrict the right of any aircraft to fly within its boundaries; it simply requires them to maintain contact with the ADIZ-holding state and to provide flight data. Ever since its adoption by the US in the aftermath of the Second World War, a number of countries have enforced an ADIZ, including Japan, South Korea, Vietnam, Russia and Canada.

China’s ADIZ

On 23 November 2013, China’s Ministry of National Defense announced the aircraft identification rules for the East China Sea ADIZ, extending about 200 miles off the Chinese coast. The ministry requires the aircraft to report its flight plans to the Chinese authorities, maintain two-way radio communications with the authorized body, keep its secondary transponder active, and clearly identify its nationality and logo. The statement indicates that in the event that an aircraft does not cooperate or refuses to follow the instructions, “China’s armed forces will adopt defensive emergency measures,” regardless of the intention of the aircraft. Later statements from the Chinese government have clarified the enforcement of the ADIZ, indicating that routine flights do not need to report to the air control center and that they will follow the normal procedures as applied by other countries.

China’s ADIZ covers most of the East China Sea, including the disputed Diaoyu Islands, and overlaps with both the ADIZ established by Japan and, with the recent extension of its own ADIZ, that established by Korea. Following the announcement, Beijing started to send airplanes to fly over its hotly-contested ADIZ which, before China claimed it as its own, used to be an exclusive Japanese ADIZ. Interestingly enough, after Chinese Su-30 and J-11 fighter jets (along with a KJ-2000 airborne radar early warning system) were dispatched into the formerly Japanese airspace on 28 November 2013, Japan lodged no protest. However, Japanese administration stated that the government carried out surveillance activity in the East China Sea, as well as the Chinese ADIZ, as before, with no prior notification to the Chinese authorities.

A stream of conflicting reports filled the news portals as to the regional airline companies’ response to the Chinese ADIZ soon after it was announced. For example, the Japan Times reported on 26 November 2013 that Japanese airlines would obey the rules of the ADIZ over the East China Sea in spite of advice by the Japanese government on the contrary. Only two days later, however, it was reported that Japanese and Korean flights defied China’s new maritime air defense zone. Airliners from Vietnam, Thailand and Malaysia, on the other hand, said that they would comply with the new East China Sea ADIZ. In Taiwan, the legislative body criticized the President Ma Ying-jeou for being too soft-handed by agreeing to submit flight plans to the Chinese authorities.

Overall, apart from the heated reaction from its Northeast Asian neighbours, China’s declaration of its ADIZ has been received with caution in the region. The largest country in Southeast Asia, Indonesia, called for calm, with Indonesian President Yudhoyono suggesting that Japan and China should keep good relations for peace in the region. Similarly, Malaysian Prime Minister Razak called on both sides to settle the existing disputes through multilateral means. The Philippines, on the other hand, categorically rejected China’s new air defense zone.

Soon after China’s move in the East China Sea, several countries, including the US and Japan, warned against a similar move by Beijing in the South China Sea. So far, the Chinese Foreign Ministry has dismissed the concerns raised by Japan and the Philippines as to the establishment of an ADIZ over the South China Sea, although there has been no explicit denial. The Foreign Ministry simply stated that “China is determined to safeguard national security” hence “no country should make comments on this matter.”   

US Reaction

The most dramatic development in the hours following China’s declaration of an ADIZ was the US’ sending of two unarmed but nuclear-capable B-52 heavy bombers over the Diaoyu/Senkaku Island chain in the East China Sea. Soon after the flight, China’s Defence Ministry stated that it “monitored the entire process, carried out identification in a timely manner, and ascertained the type of US aircraft.” The spokesman of the ministry added that “China is capable of exercising effective control over this airspace,” in an attempt to rebut the skeptics who believed that China might not have the advanced surveillance and monitoring capabilities at high altitudes. Later on, the US side confirmed that the two aircraft flew from Guam and that no flight plan was submitted in advance to the Chinese and the bombers spent less than an hour within the Chinese ADIZ.

The Obama Administration’s reaction to China’s ADIZ has been unequivocal: Secretary of State John Kerry said “the United States does not recognize that zone and does not accept it. The zone should not be implemented, and China should refrain from taking similar unilateral actions elsewhere in the region, and particularly over the South China Sea.” The US Vice President Joe Biden, too, has reiterated White House’s position on the issue. When in Tokyo, Biden accused China of changing the status quo unilaterally. In the last stop of his six-day Asia tour in December 2013, Biden met Chinese President Xi Jinping and attempted to dissuade him from aggressively enforcing the ADIZ. Obviously, the US has thus far failed to convince China to backtrack or soften its posture.

Some held that the B-52s that were sent over the East China Sea “made something of a mockery of Beijing’s” ADIZ, making Beijing “look weak and ineffectual” in its capability to match its words with concrete action. However, the many commentaries that followed a similar line of argument often missed the stated rationale of an ADIZ: that it is essentially a zone in which aircrafts are monitored but not necessarily intercepted. In any case, an aircraft that enters the designated area can identify itself or choose to not do so. With ADIZ, it remains at Beijing’s discretion to assess the risk and decide whether or not to intercept the approaching aircraft.

Nonetheless, the response of the US in dispatching strategic bombers directly into an airspace that had just been declared an ADIZ made a significant political statement. However, as one essay put it bluntly, such an action might as well be seen as “criminally reckless and phenomenally stupid.” Whatever perspective one takes, one thing seems clear: the US may be willing to go to any lengths to deter China from extending beyond the historically-set areas of influence.

The US administration is clearly dissatisfied that China’s ADIZ was a unilateral step, taken with no consultation with the US, Japan or Korea. As the ECS-ADIZ includes contested territory, US and Japan perceive it “as a deliberate effort to change the status quo, even a provocation.” Accordingly, if an aircraft obeys the new rules, it will strengthen Chinese authority over the contested islands. In addition to this, Chinese ADIZ is set to marginalize Japan’s own ADIZ and this restricts the ability of the Japanese media to claim Chinese violation of Japan’s territorial airspace – in fact, given that China’s ADIZ now overlaps with that of Japan, Beijing will have the liberty to present each non-reported flight as a violation of its own ADIZ. In this respect, the US is aware that an ADIZ is important not only because it provides a further security for China, but also gives the impression of territorial legality.

Strategic Implications

Some believe that the declaration of the ADIZ could backfire and China might find itself in an unfavorable spot vis-à-vis its regional standing and in its relations with the US. Furthermore, if China fails to live up to its promise to enforce its ADIZ, Beijing could lose prestige domestically as well as abroad. Beijing may not have the required technological capability to monitor and enforce the ADIZ, which would be another serious loss of face since the Xi administration would look weak in terms of strategy-making and risk calculation.

The US and its allies in East Asia have thus far taken the Chinese ADIZ rather seriously, partly fearing that, by having the airliners identify themselves, China in fact attempting to exercise sovereignty over the contested islands in the East China Sea. If this is the case, given that a majority of countries in the region already recognized the declared identification zone, they may be said to have acquiesced to China’s territorial claims. This may be, in fact, what prompted the US to scramble bombers minutes after the announcement of the new ADIZ rules.

Second, and perhaps more importantly, China has gained a valuable insight into the lengths the US is willing to go to with respect to the protection of its interests in this region. The Obama administration might have acted too prematurely and too aggressively, which is a strategic piece of information for Beijing. If nothing else, this has demonstrated that, for all the rhetoric as to taking no sides in the territorial disputes between China and its maritime neighbors, Washington is in fact a party to them and should be treated as such.

Indeed, even though many considered it reckless, the nuclear-capable bombers that flew through China’s ADIZ delivered a crude message. What it suggests to the rest of the world may be that if they want to get their message across, they need to acquire equal, if not larger, punitive power. This may not actually mean much for a majority of nations who hold little chance to “catch up,” but it will certainly find an echo in China, if it has not already.

As far as China’s ADIZ in the ECS is concerned, establishing the zone seems to be only a first step. Although it is a major step, the full enforcement of it may come incrementally. Strategically, it offers a considerable gain for Beijing. In the long run, the ADIZ will strengthen China’s territorial integrity and national security as well as assist the nation with its territorial claims in the East China Sea, bringing it on a more equal footing with the US. The United States, in the meantime, may have set a not-so-favorable precedent for China to follow in the near future: China could simply send a strategic bomber to the US ADIZ without notifying US authorities and claim innocent passage.

However, given the extent of the US flight activity in the areas very close to the Chinese mainland, the least Beijing can do is to monitor those activities and demand identification. From one perspective, it should not be a cause of concern for any aircraft (civilian or military) to identify themselves to the Chinese authorities if they hold no hostile intentions. Yet, as Nicholas Burns, former Undersecretary of State for Political Affairs, puts it bluntly, the US feels that it should “signal to the Chinese that we are not going to be bullied and we are going to adhere to our commitments” with respect to Japan and other allies in the region.

Invariably, Beijing will not tolerate being “bullied” by the US either, which is, in the eyes of Chinese policy-makers, a foreign power in the midst of an attempt to militarily encircle China. The US has the ultimate power to diffuse the tension in the region just as it can further escalate it, the latter being the option that it seems to have chosen so far. Players such as Japan and Korea, although they seem to play major roles, are in fact sideshows in the greater contention between China and the US. For the US, the Chinese ADIZ may serve as an opportunity to further militarize the region by playing on the fear of countries in East and Southeast Asia of a rising China. For China, it is an opportunity to demonstrate its capabilities: that China can actually enforce an ADIZ which requires, above all, long-range fighters, air defense sensors (such as over-the-horizon radars) and airborne early warning and control platforms, to project power across the first chain and beyond. We will need to wait, however, to see how things will develop in the coming months.


Serafettin Yilmaz recently received his doctoral degree from National Chengchi University’s International Doctoral Program in Asia-Pacific Studies and works as researcher in Academia Sinica in Taiwan. His research interests include Comparative Regionalism and Critical Theory. His earlier work, Afghanistan: China’s New Frontier? has previously appeared in E-IR. He can be reached at

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