Defending territorial airspace, however, should not be limited to imposing restrictions on entry. The moderate extension of early warning and precautionary capabilities, beyond the territorial airspace can greatly improve a country's response to any threat. Besides, beyond a coastal country's territorial sea are the contiguous zone and exclusive economic zone, and these areas are not equal to open seas where there is unrestricted access. Likewise, a coastal country should have the right to monitor the space adjacent to and beyond the outer edge of its territorial airspace.

Such a right is not exclusive to just a few countries and regions. China has the same right as any other country to establish an air defense identification zone. This is particularly important in the context of rapid progress in military technologies and weaponry across the world. The security landscape facing China and beyond is undergoing profound changes, and China is definitely not the only one with growing security concerns. Its southeastern region, for instance, is one of the country's most developed areas, and the airspace above comprises the country's key strategic pathway. Without an air defense identification zone over the East China Sea this region would be vulnerable to security risks via the airspace over Shanghai and neighboring coastal regions. Like the previously established air defense identification zones of other countries, China's was established for defense and is not directed against any specific country or target.

Undeniably, China's air defense identification zone over part of the East China Sea overlaps that of Japan, and that is what makes it all the more important for both sides to face squarely the question of how to avoid potential conflicts and collisions in their respective monitoring operations. It should be noted that although an air defense identification zone extends beyond a country's territorial airspace, it should not intrude upon the territorial airspace of other countries.

Japan included the Diaoyu Islands when it established its air defense identification zone 44 years ago. The inclusion of the Diaoyu Islands in China's air defense identification zone should have prompted Tokyo to reflect upon its mistake. However, instead of doing so, Tokyo is urging Beijing to withdraw its plan and playing the alarmist. That should sound the true alarm about regional stability.

The author is a Beijing-based military and legal expert.