In order to cope with the reinforcement of the Chinese government vessels and the People’s Liberation Army in terms of number, the size, and the firepower, the Japanese government has been increasing the presence of the JCG and the SDF in the areas around the Senkaku Islands. The GOJ will have to accelerate this movement. Some kind of joint exercise between the JCG and the SDF will be also considered. If the United States agrees, alliance will be able to send strong warning to Beijing. For example, Japan and the United States can more frequently hold joint military exercise in the East China Sea, as they already did in last June together with India in the waters off the east coast of Okinawa.

Having said that, we have to understand these measures would only delay the speed of Chinese provocation. China will continue to watch for a chance to challenge us. Further provocative movement by China is likely to invite more direct countermeasures by Japan in the context of the territorial issue over the Senkaku.

As for the reactive and defensive measures, the Japanese government will let the JCG execute the law-enforcement over the Chinese fishing vessels in the territorial waters around the Senkaku Islands. If the Chinese fishing vessels try to catch marine products, the JCG will have to arrest them. Even if Chinese fishermen don’t fish, the JCG can question them and try to ship on board on them for inspection. The probability of the JCG’s taking such actions will be higher if the Chinese side repeats intrusions similar to Aug. 5 incident.

As for the proactive and offensive measures, the Japanese government will try to strengthen effective control of the Senkaku Islands. If China tries to weaken Japan’s effective control of the Senkaku Islands, it would be natural for the Japanese government to consider re-strengthening it in ways the GOJ has so far refrained from undertaking. The construction of the port or helipad on the isle, stationing of the JCG or the police officers on the isle, visit to the Senkaku Islands by government officials and politicians are the examples of possible countermeasures.

As you can easily imagine, however, the Chinese government may not acquiesce to these countermeasures. When the JCG vessels try to inspect Chinese fishing boats, China’s government vessels will possibly obstruct the JCG’s act of law-enforcement. Likewise, if the Japanese government decides to build a helipad on the isle, China may try to block Japan’s transporting materials and personnel. In either case, the result will be a clash between the JCG and Chinese maritime policing vessels. Government vessels of both countries may turn on water cannon, collide with the ships, or even fire autocannon. As the Chinese maritime policing agencies have been increasing the size and firepower of vessels, we should expect at least some casualties.

The clash may not end there. Behind the vessels and aircrafts of the two coast guards, the SDF and the PLA are engaged with reconnaissance and surveillance. The leader of the country whose maritime policing agency is put in disadvantageous position may order its military to help the coast guards. In turn, the leader of the other country will have to consider sending its military to the sea area. Then, it is only a step to the real military conflict between Japan and the PRC.

Needless to say, the cost of military conflict is huge, or even catastrophic for both Japan and China. Besides human casualties, the bilateral trade, amounting more than 300 billion dollars annually, will be suspended. The trade and investment with other countries will also be heavily damaged. Not only will the capital markets of the two countries plunge as foreign investors escape, the military conflict between the second largest economy and the third will hit very hard the global economy and financial market as a whole. With these sheer facts, conventional wisdom is that both Japanese and Chinese leaders will not think they can fight each other. I was one of those who believed so. But I am no longer confident in this theory.

The first reason is simple. The more the Chinese government vessels (and the PLA behind them) stay in the territorial waters around the Senkaku Islands and adjacent area, the more chances of encounter between the Chinese and Japanese maritime policing vessels (and military forces behand them), and thus the more chances of conflict, including the accidental one.

Secondly and more fundamentally, the calculus is changing rapidly in a way to challenge conventional wisdom.

For a long time, China simply lacked the ability to challenge Japan’s claim of sovereignty over the Senkaku Islands. When they did not have the ability to project its coast guards and military forces in the East China Sea, China could gain more from preserving the status quo. Now, Beijing can constantly send patrol vessels from the continent and match the size and firepower of the JCG vessels. The modernization of the PLA enables the continued expansion of its sphere of activity. With this ability in hands, Chinese leadership may consider that they can gain more points not from self-restraints, but from provocative action in the game over the Senkaku’s sovereignty. Inaction could also mean a fixation of the disadvantageous Chinese position following a decision of the Japanese government to nationalize three isles of the Senkaku Islands in September 2012.

On the other hand, Tokyo has long favored the status quo. Because it can effectively govern the Senkaku Islands, endurance has basically brought more gain for Japan. But recently, the loss from endurance has become more and more visible and problematic.

In the past, Chinese challenge to Japanese sovereignty over the Senkaku —illegal landing by the Chinese activists at the Uotsuri Island in 2004 and 2012 and illegal fishing by the Chinese fishermen in the territorial waters around them in 2010— occurred sporadically, and the Chinese government vessel was not at least directly involved. Japanese coast guard or police agency could arrest the Chinese for violation of the Japanese laws. By that, Japan could prove that the Senkaku Islands are governed by the Japanese government. With this calculation, the government thought it acceptable, if not desirable, to release the Chinese detainees without putting them on Japan’s trial. However, if the Chinese government generates a situation where the Japanese government cannot execute its law in the territorial waters around the Senkaku Islands, the loss from self-restraints will be too significant for Tokyo to ignore.

The Japanese government as well as most Japanese people has given up receiving rewards from their endurance. Although the United States is not satisfied with China’s behavior at all, Washington can sometimes do business with Beijing. The ratification of the Paris Agreement to combat climate change is the recent example. Japan’s disappointment over China is far greater. Lost incentive to accommodate China may push the back of Tokyo to take harder lines. (The same thing can be pointed out about the psychology of the Chinese policy makers.)