Should Beijing Establish an Air Defense Identification Zone Over the South China Sea?

Chinese military officials are hinting that they might. But it only makes sense if Washington keep playing the heavy.


In November 2013, Beijing surprised everyone — both inside and outside China — by declaring an Air Defense Identification Zone (ADIZ) over the East China Sea.

An ADIZ extends a country’s airspace, allowing it more time to respond to foreign, and possibly hostile, aircraft. Almost all analysts inside China, including many affiliated with the Ministry of Foreign Affairs, opposed the East China Sea ADIZ: They saw it as an unnecessary provocation — and one that could further destabilize China’s already tense relationship with Japan. But China’s military, the People’s Liberation Army (PLA), seems to have dominated the decision-making process, ensuring a more aggressive posture.

Until the current round of tensions between the United States and China over Beijing’s land reclamation in the South China Sea ratcheted up in April, few were debating whether China would establish an ADIZ in the region. Now, Beijing is publically hinting that it might: On May 31, at the Shangri-La Dialogue, an important annual security conference in Singapore, PLA Adm. Sun Jianguo said that China could set up another ADIZ — if it feels that it’s facing a large enough threat in the South China Sea.

But should China establish an ADIZ over the South China Sea? It is instructive to compare the current context with the situation that led Beijing to declare an ADIZ in the East China Sea. In September 2012, the Japanese government triggered a confrontation by “nationalizing” the Diaoyu Islands (both countries claim these small, rocky outcroppings, but they are under de facto Japanese control). In response, for the next 14 months, Beijing challenged Japanese control by sending surveillance vessels and patrol aircraft near the islands.

Back then (as today), the Chinese foreign policy community displayed little enthusiasm for an ADIZ. But PLA military planners concluded that merely sending vessels and aircraft to the region didn’t go far enough in asserting Chinese sovereignty — since it didn’t change the reality of Japanese control. By imposing an ADIZ over the Diaoyu, the PLA gave the impression of strengthening China’s sovereignty over the islands. (That was probably why Beijing insisted that all aircraft flying through the ADIZ must identify themselves — in contrast to the customary practice that only aircraft that plan to enter a nation’s airspace need to identify themselves.)

There was also an important element of strategic surprise in the decision: Beijing had never established an ADIZ before, and few were expecting it to escalate an already tense confrontation with Tokyo over the Diaoyu. Although the ADIZ angered many in the Japanese and American policy community, Beijing concluded that it successfully expanded China’s strategic space in the Western Pacific and entrenched a new strategic status quo in Northeast Asia. Domestically, it also quelled nationalistic voices that were pushing for a muscular response to perceived Japanese infringement on Chinese sovereignty. More broadly, the decision reflected Beijing’s determination to transform the past passive and reactive approach of Chinese foreign policy to a much more proactive and assertive one.

Will Chinese planners come to similar conclusions regarding an ADIZ over the South China Sea? Perhaps not — and there are several reasons that hint at a different outcome.

First, announcing an ADIZ over the South China Sea now would achieve no strategic surprise, since the issue has already become an international concern.

The second relates to the question of de facto control. The most crucial difference between Chinese positions in the East China Sea and the South China Sea is that, in the former, Beijing has no actual control over the Diaoyu; in the latter, it does control some of the maritime features. Thus Beijing does not need to establish an ADIZ to make a point about sovereignty over islands and reefs it already controls. And there’s little need to further pressure or intimidate claimant states such as Vietnam and the Philippines, since these countries have little ability to wrest control of the shoals and reefs from Beijing.

Third, nationalists are not currently pressuring Beijing to take a tougher approach toward the South China Sea, largely because Chinese policies in the past two years have already demonstrated to the public that the government will stand up to outside pressure if core interests are at stake.

And fourth, imposing an ADIZ will have serious negative consequences for China’s generally good relations with many Southeast Asian countries, and with the regional body, the Association of Southeast Asian Nations (ASEAN). Why should Beijing want to damage those relationships, when promoting a 21st-century maritime Silk Road through Southeast Asia represents a far more important priority for President Xi Jinping?

Finally, there is also the very thorny technical problem of trying to set up an ADIZ over the South China Sea: The more than 40 tiny features in the Spratly Islands occupied by claimant states are very close to one another. China’s Johnson South Reef, for example, is less than 4 nautical miles from Collins Reef, which Vietnam occupies — within the 12 nautical miles that China might assert as its territorial surrounding sea. How should China determine the radius of its ADIZ from its islands and reefs without creating further tensions with other claimant states?

In short, unless the South China Sea situation worsens, it’s highly unlikely that Beijing will announce another ADIZ.

It will probably occur only if Beijing has greater ambitions than the current reclamation of maritime features already under its control: for instance, absorbing all waters and resources — not just the atolls, reefs, and rocks — within the so-called “nine-dashed line.” (Outside observers take the “nine-dashed line” as Beijing’s claim to the vast majority of the South China Sea. Note, however, that Beijing has never clarified what this actually means; its real goal is almost certainly not nearly that expansive.)

Whether China will establish an ADIZ over the South China Sea will likely depend, therefore, on U.S. policy and on the level of America’s military involvement in the region. Beijing and Washington should work to keep the South China Sea tension at the diplomatic level, without escalating it to a military confrontation. At the diplomatic level, the disputes are manageable — especially because policy planners don’t have to worry about the complicated implications of a Chinese ADIZ over the South China Sea. But if tensions escalate into the military arena, the Chinese military will once again dominate decision-making by overriding the foreign-policy establishment. And that could mean another ADIZ — and a worryingly high level of tension.

Zhou Fangyin, a professor at the Guangdong Research Institute for International Strategies, contributed research to this article.