This month marks the tenth anniversary of Japan’s nationalization of the Senkaku Islands, when the Japanese government purchased them from a private landowner in an effort to reinforce administrative control and to prevent private groups from visiting. The Chinese response to Japan’s action—which was controversial at the time—sparked a crisis in bilateral relations; although there had been incidents of Chinese ship incursions into waters around the islands previously, the numbers surged dramatically after September 2012. For the rest of the year and throughout much of 2013, the China Coast Guard (CCG) sustained a heavy presence around the islands, with ships entering the contiguous zone dozens of times each month, and incursions into territorial waters occurring at times almost daily. During this period, Japan deployed nearly half of its entire Coast Guard fleet in response to the challenge.

Ten years later, it is hard to appreciate the level of concern in Washington (and Tokyo) at the time about the risk of a conflict over the islands. In retrospect, the response by Japan and the United States to the 2012 crisis proved to be effective in forcing Beijing to back down and restoring relative equilibrium in the area.  PRC pressure on the islands and along the two countries’ maritime boundary in the East China Sea (ECS) continues to this day—as AMTI’s identification of a new permanent oil rig on China’s side of the ECS mid-line demonstrates—and Beijing’s ultimate objective of securing control over the area almost certainly remains unchanged. But Japanese and U.S. actions succeeded in preventing a conflict that seemed imminent at the time, and bought a decade of relative stability thereafter.

As events escalated in late 2012 and into 2013, Japan and the United States took a series of steps to push back on PRC maritime pressure. First, the allies reinforced declaratory policy related to U.S. security commitments. In a January 2013 press conference with new Foreign Minister Fumio Kishida, Secretary of State Hillary Clinton reaffirmed that Article V of the Mutual Security Treaty applies to the Senkaku Islands, a statement she had previously made in 2010. This message was echoed privately at senior levels in Beijing, with U.S. officials underscoring the seriousness of U.S. commitment and warning that China should not miscalculate. The allies proceeded to elevate and repeat this messaging—President Obama verbally affirmed the U.S. commitment to the Senkakus for the first time at the presidential level during an April 2014 visit to Tokyo, and again in April 2015 when then-Prime Minister Abe visited Washington. (Presidents Trump and Biden have since repeated the U.S. position in writing, in multiple joint statements since 2017.) The United States also took more tangible actions to reject PRC claims. For example, just three days after Beijing unilaterally declared an Air Defense Identification Zone (ADIZ) in the ECS in November 2013, two B-52 bombers ignored China’s “requirement” for prior notification in transiting the area.  There was no Chinese response.

In addition to these short-term actions, the allies took longer term steps as well. Japan began a sustained build-up of both Self Defense Force and Coast Guard presence in Okinawa and the Ryukyu chain. In particular, the Coast Guard expanded infrastructure on Ishigaki Island to accommodate 12 large patrol ships and 600 personnel—making Ishigaki home to the largest Japan Coast Guard (JCG) facility in Japan. In combination with ships based on Okinawa, the build-up has enabled the JCG to consistently match the numbers of CCG ships operating near the Senkakus. In addition, the United States and Japan for the first time undertook military contingency planning for an ECS crisis, and U.S. forces began periodic presence operations near the islands, including occasional flights by strategic bombers in the area that China was certain to detect. And Japan sustained regular public messaging that spotlighted Chinese intrusions near the islands, including monthly publication of a chart documenting the number of maritime incursions into waters around the Senkakus.

This combination of consistent public messaging regarding Chinese actions; clear declaratory policy, repeated frequently at multiple levels; and physical demonstrations of resolve, both unilaterally and in an alliance context, and sustained over time, arguably forced China to adjust course.  By the end of 2013, the number of CCG incursions into territorial waters around the Senkakus began to drop off, lowering the sense of immediate crisis; with the exception of a brief period in 2016, the numbers have never returned to 2012 levels. CCG presence and regular incursions into territorial waters have continued in the years since, but they have stabilized in number and taken on a routine character that a Japan Ministry of Defense official describes as a “box-checking exercise,” one that allows China to assert its claims without sparking a crisis. And despite expectations that it would do so, China has not declared an ADIZ over the South China Sea—perhaps in part because of the backlash it received for doing so in the East China Sea.

Of course, this movie has not ended, and China is taking steps that will continue increase pressure on Japan and test the alliance’s response. The size of CCG ships operating in the area is getting larger, for example.  In 2012, Japan had more 1000-ton ships in its Coast Guard fleet than did China (51-41); today, the CCG has double the number of such ships in the JCG. The number of CCG incursions into the contiguous zone around the Senkaku Islands also has grown again, perhaps signaling an intent to increase territorial water incursions as well. Just this week, three CCG vessels entered the territorial waters around the Senkakus and lingered for more than eight hours. And in 2020, China revised its Coast Guard Law to allow its ships to use force against foreign parties deemed to have violated the country’s sovereignty. With China increasing the overall size of the CCG, Japan will have to develop a strategy for responding to incursions that does not involve numerically matching the number of ships on the water.

The stand-off in the East China Sea has receded from the headlines, but remains a low boil flashpoint. Nevertheless, the relative stability today in the East China Sea was not a foregone conclusion during the height of the crisis in late 2012, and the combined Japanese and U.S. response offers lessons for responding to PRC maritime coercion.

About Christopher B. Johnstone

Christopher B. Johnstone is senior adviser and Japan Chair at the Center for Strategic and International Studies (CSIS).