This analysis is the third of four chapters in a CSIS examination of security dynamics in the East China Sea and the implications for the U.S.-Japan alliance. The first chapter can be read here, the second here, and the fourth here.

While the trends in the East China Sea have been concerning, Japan and China have been able to avoid a major incident in the area over the last five years. Yet, with Chinese capabilities improving and the margin of the Japan-U.S. alliance’s supremacy narrowing, the likelihood of an incident is growing.

This section reviews several potential incidents that could arise and describes how each might challenge Japan, the United States, and their existing alliance mechanisms. It discusses five possible incidents: fishing clashes at sea, a collision on or around the Senkaku Islands, the deployment of an oil rig over the median line, a challenge to aircraft operating in China’s East China Sea Air Defense Identification Zone, and a military escalation involving unmanned systems.

Fishing Clashes in the East China Sea

Fishing incidents have been commonplace in the South China Sea, but Beijing has appeared to attempt to control these incidents in recent years in the East China Sea. Nevertheless, a serious clash between fishing and coast guard vessels seems inevitable, unless the region’s maritime disputes are fully resolved. In the past, these incidents have demonstrated substantial escalatory potential, as was the case in 2010 when a Chinese fisherman intentionally collided with Japanese coast guard vessels. The resulting dispute played a large part in escalating tensions in the East China Sea, so such a scenario could once again pose a serious threat to regional security.

At the core of this dispute are the conflicting maritime claims of China, Taiwan, and Japan. Japan’s claimed exclusive economic zone ranges from the Ryukyu Islands to what it asserts is the median line between the Chinese and Japanese continental shelves in the East China Sea. China and Taiwan, however, maintain that their exclusive economic zones could include nearly all of the East China Sea, given their extensive continental shelf claims. A related potential challenge is that the Chinese government limits fishing within most of the East China Sea for much of the year. The annual end of the fishing ban typically results in large numbers of Chinese fishing crews venturing into the East China Sea, including into the contiguous zone and territorial sea around the Senkaku Islands. As a result, it is conceivable that either Japanese or Chinese coast guard ships could clash with fishing vessels from the other country or from Taiwan.

Fishing clashes are serious concerns, not only because the fishing crews themselves could be injured and require emergency responses, but also because fishing rights are intertwined with sovereignty claims, which leads regional governments to see fishing disputes through a nationalistic lens. China has an estimated 50,000-plus fishing vessels, many of which are ocean-going, with several hundred often appearing in the East China Sea at the end of the yearly fishing ban. Although these numbers decreased in 2017, the expectation is that Chinese fishing and coast guard vessels will increase their presence in the disputed portions of the East China Sea in the years ahead.

Incidents on or around the Senkaku Islands

Since the 2010 clash between a Chinese fishing vessel and the Japan Coast Guard, much attention has been paid to the potential for additional incidents on or around the Senkaku Islands. Leaders in Beijing and Taipei periodically feel a need to demonstrate that they do not recognize Japanese claims to the Senkakus, which they do in part by sailing or flying within the territorial sea (or contiguous zone) around the islands. For their part, Japanese leaders seek to respond to these efforts by monitoring foreign vessels and aircraft with their own assets, typically from either the Japan Coast Guard or the Air Self-Defense Force.

It is easy to envision a serious crisis emerging from these interactions. For example, if a ship or aircraft were disabled, its crew might seek refuge on one of the Senkaku Islands. This would likely cause a major international incident because, regardless of which party were to land on the Senkakus, the other(s) would be forced to respond. If Chinese fishing crews, coast guardsmen, or military members landed on the Senkakus, then the Japan Coast Guard would no doubt seek to remove them in a law enforcement action. But given that China does not recognize Japan’s claims, it is certainly possible that Beijing could see this as an escalation, which might result in a substantial military response from China.

Another concerning scenario is a worsening of the daily operating tempo in the East China Sea. The Japan Coast Guard and Self-Defense Forces are already stretched thin in an effort to respond to the activities of the Chinese fishing fleet and government vessels and aircraft. If these operations increased in frequency, it would pose a substantial burden for Japan. Moreover, greater frequency of operations might be accompanied by greater assertiveness in interactions, including more physical contact between ships (such as shouldering) and closer intercepts between aircraft. The prospect of more frequent and more aggressive air and sea encounters poses a clear risk not only of escalation, but also of greater operational stresses on both Japanese and American forces.

Deployment of Oil Rigs over the Median Line

One of the most concerning recent trends in the East China Sea is the increasing number of Chinese oil and gas exploration and drilling rigs in the area. Many of these rigs are believed to hold advanced radars, helipads, and other facilities, which could be used for military as well as civilian purposes. As a result, policymakers in Tokyo have been increasingly concerned about the potential for the People’s Liberation Army to use these fixed platforms to project power deeper into the East China Sea.

A particularly concerning scenario would be the deployment of one or more of these oil and gas rigs across the median line of the East China Sea, which Japan claims as the boundary between its continental shelf and that of China. If this were to occur, Japanese policymakers would be forced to consider ways to convince China to withdraw the rig, or to accept a substantial change to the status quo. After all, Beijing’s activities to the east of Japan’s claimed East China Sea median line have to-date relied on mobile platforms, rather than fixed positions. This is quite different than the situation in the South China Sea, where China has constructed fixed positions on disputed features. Permanent positioning of drilling rigs in the East China Sea could serve a similar function, providing a permanent presence and thereby aiding Chinese operations in the East China Sea.

This would be similar in many ways to the situation that occurred in the South China Sea in May 2014, when the China National Offshore Oil Corporation placed oil platform Hai Yang Shi You 981 (HYSY-981) into a disputed area in the Paracel Islands that is within Vietnam’s claimed exclusive economic zone. At the time, Vietnam chose to accept significant operational and strategic risk during the ensuing months-long confrontation, which eventually led to the sinking of a number of Vietnamese vessels and prolonged economic pressure from Beijing. This experience demonstrates that there is substantial escalatory potential in the deployment of oil rigs in disputed waters. Therefore, Japanese leaders must remain attentive to any such efforts, and be prepared to respond before Beijing can accomplish a fait accompli.

Challenges to Aircraft in China’s East China Sea Air Defense Identification Zone

In November 2013, Beijing announced an Air Defense Identification Zone (ADIZ) covering much of the East China Sea. Although the United States and Japan refused to acknowledge some of the rules that China attempted to apply in its ADIZ, most commercial airlines have adhered to the ADIZ requirements for prior notification of flights through the zone. For the most part, however, China has not attempted to physically enforce the ADIZ by intercepting either civilian or military aircraft that are not observing its rules.

Most experts believe that China has not enforced its ADIZ in part because it has not always been capable of identifying, tracking, and intercepting aircraft flying through the entirety of the East China Sea. Yet, China’s improving air and maritime surveillance capabilities may permit it to detect most aircraft—except perhaps the stealthiest airframes—in the East China Sea in the years ahead. This is the product not only of the growing range and sensitivity of Chinese ground-based radar systems, but also their fleet of airborne early warning and control aircraft, particularly the KJ-3000 and the KJ-600, a carrier-launched version.


Using these more advanced systems, potentially in coordination with air-to-air refueling, Chinese leaders might opt to enforce the ADIZ by challenging foreign aircraft operating without filing flight plans in the zone. Perhaps the most concerning targets for fighter jet intercepts would be unarmed military aircraft, such as maritime domain awareness and signals intelligence gathering platforms, which often fly through these areas. In the past, Chinese pilots have occasionally challenged these aircraft, but more frequent or aggressive challenges could lead to a major incident, as occurred in the 2001 EP-3 crisis. Furthermore, the increased reliance on unmanned systems, by both China and the Japan-U.S. alliance, would force allies to develop new tactics, techniques, and procedures for operating within a more contested airspace.


Military Escalation Involving Unmanned Systems

A fifth potential scenario that could lead to increased tensions in the East China Sea is a military escalation involving one or more unmanned systems. The growing use of unmanned systems, both in the air and undersea, has created an increasingly dense operational picture for regional militaries. The unique characteristics of unmanned systems often make them valuable for long endurance missions, such as detecting and tracking submarines as well as conducting intelligence, surveillance, and reconnaissance missions. These same attributes, however, also make undersea systems tempting military targets for potential competitors.

In 2016, the Chinese military captured a small unmanned submersible, which was being operated by the U.S. Navy in international waters off the Philippine coast. China later returned the system, but the ensuing tensions raised the temperature in the region. A similar situation could certainly take part in the East China Sea. Such an action could be intended to alter the rules and norms surrounding operations of military systems within a claimed exclusive economic zone. The seizure of an unmanned system poses substantial escalation risks because the side that suffers the seizure is likely to respond, either in an effort to force the return of the system or to force its opponent to pay a cost for such escalatory actions.

In the East China Sea, there have already been concerns not only about undersea gliders, but also about unmanned aerial vehicles. Another area of concern is interference with space systems, to include global positioning and timing satellites and signals as well as remote sensing satellites. Although interference with unmanned systems typically does not cause a loss of life and is therefore seen as a lower form of escalation that engaging in kinetic action against a manned platform, a serious incident or emerging pattern of incidents might trigger an escalatory spiral that could include not just unmanned systems, but manned systems as well.

Header image courtesy of Al Jazeera English Flickr account.

About Zack Cooper

Zack Cooper is a research fellow at the American Enterprise Institute. Previously, he was senior fellow for Asian security at the Center for Strategic and International Studies. He has also served on staff at the National Security Council and in the Office of the Secretary of Defense. He received a B.A. from Stanford University and an M.P.A., M.A., and Ph.D. from Princeton University.