China and Japan have an incentive to act and reduce tensions before things get worse.

At the recent Shangri La Dialogue, Japanese Prime Minister Shinzo Abe and Chinese Lieutenant General Wang Guanzhong traded verbal barbs regarding each other’s countries’ regional behavior. Abe, clarifying his support for ASEAN states locked in territorial disputes with China in the South China Sea, stressed the importance of international law, indirectly criticizing China’s approach to territorial disputes. Wang, in turn, accused Abe of being provocative and trying to stir up trouble. While making for good drama, the verbal barbs reflect an increasingly dangerous situation playing out in the East China Sea that carries real-world consequences that may prove difficult to deescalate. Assuming neither country is willing to risk unintended conflict, it behooves Beijing and Tokyo to discuss mutual rules of interaction between their military forces.

At issue is an incident between military aircraft that took place on May 24. Chinese SU-27 jet fighters flew incredibly close to two Japanese surveillance planes, within fifty meters of a Maritime Self-Defense Force OP-3C aircraft and within thirty meters of an Air Self-Defense Force YS-11EB aircraft. The area where the incident took place was several hundred kilometers north of the Japanese-administered Senkaku Islands (“Diaoyu” in Chinese) and in an overlapping region of both countries’ Air Defense Identification Zones (ADIZ), areas where states ask aircraft to identify themselves and provide flight plans.

Disputed, however, is the circumstance of the event. China initially argued the Japanese aircraft entered an area where China and Russia were conducting joint naval exercises, thereby forcing China to scramble jets to meet the Japanese aircraft that were monitoring and interfering with the exercise (i.e. being provocative). Japan denies this account, arguing not only did the incident take place outside the exercise area but that it was carrying out routine information-gathering operations over the high seas, an activity backed by international law. China then piled on a separate argument, saying its planes were defending its ADIZ against Japanese provocations.

So, who is at fault? Examining these few certainties against the corpus of international law defining state behavior in international waters/airspace provides different perspectives. First, consider the activity of each military. Because the incident occurred over high seas, according to most interpretations of international law, there are no restrictions on Japan performing information gathering. Likewise, there are no restrictions on China and Russia performing joint exercises. From this perspective, both sides’ behavior is backed by international law.

Yet, while there is no international law that prescribes behavior regarding joint exercises in international waters, it is considered prudent to avoid an area until after the completion of an exercise. If Japan entered into an area where China and Russia were undertaking joint exercises, then Japan would be at fault (although not legally), particularly because China released a no-fly notice prior to the exercises. This point appears to be moot, however, as Japan vehemently denies China’s claim.

Legal arguments that are consistent generally have greater authority. Yet, China convoluted its argument by also saying it was defending its ADIZ. Under international law, there is no legal support for the sovereignty of one’s ADIZ apart from the airspace above one’s territorial sea. Under the UN Convention on the Law of the Sea (UNCLOS), this translates to a maximum of twelve nautical miles from one’s shores. China’s position of defending its ADIZ from Japanese provocation far from its shores, therefore, lacks a basis in international law.

Regardless of these differences, one point stands out. There is a practice among pilots to maintain safe distances between aircraft. Japan, for instance, maintains a distance of several hundred meters from other aircraft when it scrambles its jets. To send warnings to foreign aircraft, its aircraft will usually flap their wings or radio an alert. The Chinese aircrafts failed to provide any such signaling; rather, they flew dangerously close, thereby risking the lives of both Chinese and Japanese pilots. Given China’s jet fighters are faster and more maneuverable than Japan’s propeller planes, the blame for the dangerous behavior falls solely on China.

This brings us to finger-pointing at China (once again). Similar to Abe Denmark’s recent observations in the National Interest about the South China Sea, Beijing’s modus operandi in the East China Sea is to couch its actions as reactions to perceived provocations from Japan. In this case, it was to defend China’s ADIZ against a Japanese intrusion. What Chinese leaders fail to recognize is the self-defeating nature of its behavior. Chinese actions in both the South and East China Seas frighten periphery states, thereby making Abe’s efforts to play hardball with China that much easier.

But this trend is worrisome, because as China engages in more provocative behavior short of war in the East China Sea, Japan continues to match China’s assertiveness. This tit-for-tat behavior leaves room for mistakes that could have disastrous consequences. One need only think of the 2001 EP-3 incident—on steroids.