China’s recent announcement of an Air Defense Identification Zone in the East China Sea has generated a great deal of confusion and alarm. Much of that is a function of the fact that few know what an ADIZ is, what it is for, and why it matters -- including, apparently, the Chinese government and military.

An ADIZ is a publicly defined area extending beyond national territory in which unidentified aircraft are liable to be interrogated and, if necessary, intercepted for identification before they cross into sovereign airspace. The concept is a product of the Cold War: in the 1950s, the United States declared the world’s first ADIZs to reduce the risk of a surprise attack from the Soviet Union. Today, the United States has five zones (East Coast, West Coast, Alaska, Hawaii, and Guam) and operates two more jointly with Canada. Other countries that maintain ADIZs include India, Japan, Norway, Pakistan, South Korea, Taiwan, and the United Kingdom.

In addition to providing an added measure of security, an ADIZ can help reduce the risk of midair collisions, combat illicit drug flows, facilitate search-and-rescue missions, and reduce the need for fighter jet sorties for purposes of visual inspection. This last point is the most important: ADIZs can increase transparency, predictability, and strategic stability by reducing uncertainty on both sides about when, where, and how aerial interceptions might take place. In 1960, for example, the Soviet Union had no clearly established air defense identification zones and procedures, and the resulting confusion led to a U.S. reconnaissance aircraft being shot down over international waters.

There are no international agreements governing any aspect of an ADIZ. States are neither explicitly authorized to establish them nor are they explicitly prohibited from doing so. ADIZs usually extend into what is universally acknowledged to be international airspace, even by the countries that maintain them, and in no way confer any sovereign rights. Off southern California, for example, a U.S. ADIZ stretches more than 400 miles out to sea. Since states have the right to regulate air traffic only over their sovereign territory, countries are not legally obliged to comply with another countries’ ADIZ requirements in international airspace, but they tend to do so because of the security and safety benefits to all. An air defense identification zone is about security and safety, not politics or law.

So why did China establish its East China Sea ADIZ?

Reducing the risk of surprise attack cannot have been part of the equation, because there was no real danger of that to begin with. Tensions in the region are undoubtedly high at the moment, but this is not your grandfather’s Cold War. No country wants a major shot to the heart of the global economy. The danger of surprise attack is highest when at least one party to a conflict considers war inevitable and thinks that getting in the first blow would deliver a decisive military advantage. To the extent that China’s ADIZ has deepened regional fears about China’s long-term intentions, it has actually increased this risk.

Also implausible is that China sought to reduce drug smuggling in the East China Sea, which is not a significant drug route. And given the multiple and overlapping maritime jurisdiction claims in the area, there is no shortage of willing search-and-rescue providers. Not surprisingly, neither motive figured in the Chinese defense ministry's statement announcing the establishment of the zone.

The desire to reduce the risk of midair collisions is a marginally more plausible explanation. The problem here is not commercial air traffic, which is already under good regulation in the East China Sea (anyone with an Internet connection can monitor it in real time). Rather, it is military flights, as was demonstrated in 2001 when a U.S. Navy EP-3 collided with an F-8 fighter from the Chinese Navy over the South China Sea.

In the case of military flights, the risk of midair collision primarily stems from conflicting understandings of overflight rights. Most countries insist that their militaries have a right to fly freely in international airspace. The United States allows this even within its own ADIZs, subject to possible observation. By contrast, China and a small number of other like-minded countries, including Brazil, insist that a coastal state has the right to regulate at least some military traffic in the airspace over its exclusive economic zone (EEZ) -- the maritime area extending 200 miles from its shores over which it has special exploration and resource exploitation rights. This difference of opinion led directly to the EP-3 incident: the pilot that intercepted the American plane took exception to its presence in China’s EEZ and in the process of attempting to scare it away clipped its wings. Since proclaiming an ADIZ puts even more pressure on China to intercept foreign military flights, it actually increases the risk of such accidents.

It is evident that China’s ADIZ has no prospect of increasing transparency, predictability, or strategic stability. It has prompted confusion among commercial airlines and ostentatious demonstrations of noncompliance by the U.S., Japanese, and South Korean militaries. Since China’s ADIZ overlaps with Japan’s, there is now a very real possibility that a plane in the area could receive conflicting instructions and face simultaneous Chinese and Japanese interception. From a security and safety perspective, China’s announcement clearly makes things worse, not better.

The common wisdom, no less wise for being common, is that China declared an ADIZ in the belief that it would aid in its dispute with Japan over the Senkaku (Diaoyu) Islands. Chinese leaders could have believed this for one of two reasons: first, they believed that an ADIZ signals or confers sovereign rights; or, second, they believed that declaring an ADIZ covering the disputed islands would enhance their bargaining position. The former is demonstrably wrong; if this is what they believed, they should immediately fire their international lawyers. The latter belief would only be justified if bargaining was taking place and if Washington and Tokyo could be cowed. This has proved demonstrably wrong, too, and if this is what they had in mind, they should fire their political analysts.

It is evident that China miscalculated. But China is not the only country that is worse off as a result. East Asia has suddenly become a more dangerous place.

It is unrealistic to expect China to walk back its ADIZ unilaterally. That would be a major embarrassment both for the Chinese military and for the regime, both internationally and domestically. But strident noncompliance represents an embarrassing loss of face for Beijing as well. It also reinforces Chinese misconceptions about the legal implications of an ADIZ. So too does South Korea’s tit-for-tat expansion of its own air defense identification zone, which will only further increase the dangers of inadvertent confrontation. By taking a hard line, China’s adversaries have put Beijing in an even bigger bind.

Sometimes when someone does something embarrassing in public, the smart thing to do is to pretend not to notice. Admittedly, this is now somewhat difficult; Seoul, Tokyo, and Washington have already reacted. But they can drop the subject publicly and start quietly arranging some rules of the road with Beijing, behind the scenes, that let it save face while operationally returning to the status quo ante.

China is on record having established an East China Sea ADIZ; the United States and its allies are on record having rejected it. Let the public conversation end there. At the end of the day -- as far as sovereignty is concerned -- it is all much ado about nothing anyway.