This analysis is the first 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 second chapter can be viewed here, the third viewed here, and the fourth here

Over the last five years, many volumes have been written about the South China Sea. China’s construction of artificial islands on disputed features in the Spratly Islands has combined with fishing clashes, resource competitions, and freedom of navigation operations to focus substantial international attention on the situation in the South China Sea. Yet, perhaps the most potentially explosive situation in maritime Asia lies to the north, in the East China Sea. Yet, with a few notable exceptions, the East China Sea has received relatively less attention.

Whereas China is increasingly poised to dominate the South China Sea, this is not the case in the East China Sea, at present. Few of China’s rivals in the South China Sea have the capability to challenge Beijing’s overreaching claims, and fewer still have the willingness to do so. Even Vietnam, which has been the most risk acceptant South China Sea claimant, has recently suspended oil and gas projects in its own exclusive economic zone (EEZ) in the face of Chinese pressure. In the East China Sea, however, Japan has demonstrated both the capability and the intent to uphold its claims and push back against Chinese assertiveness. Moreover, the United States has shown greater willingness to stand behind Japan in upholding its maritime claims, which has not always been the case with regard to U.S. commitments to the Philippines.

With Chinese construction in the South China Sea nearly finished and its political influence neutralizing potential challengers, Beijing’s attention is likely to shift elsewhere in the years ahead. Although the Taiwan Strait is an obvious candidate for renewed tensions, the East China Sea is perhaps riper for a renewed contest of wills. Tensions in the East China Sea have subsided since 2012, but that temporary decrease should not be interpreted as a permanent stabilization of the regional security environment. Chinese leaders have a tendency to push their agenda forward in one region while practicing restraint in other regions. Much of China’s focus over the last five years has been on the South China Sea, but with China’s projects in the South China Sea nearing completion, Beijing may be preparing to turn back to the East China Sea.

When Beijing does shift focus to the East China Sea, it will find a much more favorable situation there than that which existed in 2012. The balance of forces in 2020 will include a far more capable set of Chinese government and government-affiliated actors. The People’s Liberation Army Navy (PLAN) has expanded substantially and is increasingly fielding highly-capable forces with improved experience exercising joint operations involving air and naval forces. China’s coast guard has also grown rapidly in both the number and size of the vessels that it fields, including well-armed coast guard ships. Furthermore, the Chinese fishing fleet and maritime militia are more capable and better coordinated today than they were in 2012.

How might China use these new capabilities to achieve its objectives in the East China Sea? Beijing could use its fishing fleet, maritime militia, or coast guard to contest administrative control of the Senkaku Islands (Diaoyu Islands in Chinese—this essay uses Senkaku Islands in accordance with the U.S. Board of Geographic Names). Alternatively, Beijing could attempt to exploit fishing or oil and gas resources across the median line in the East China Sea. Moreover, China could use economic measures to pressure Japanese businesses into changing their behavior or that of the Japanese government. Although the Japan Coast Guard and Japan Self-Defense Forces (JSDF) have been preparing for an increase in Chinese pressure in the East China Sea, the pace of China’s military and paramilitary modernization programs will prove difficult to match. Therefore, Japan and the United States are likely to find themselves in a more disadvantageous position in the years ahead than they were in the 2010 and 2012 East China Sea crises.

This study explores the changing patterns of Chinese behavior in the East China Sea and describes the expected balance of forces in the years ahead, including the rapid growth in Chinese capabilities. The next section includes projections of Chinese, Japanese, and U.S. force structures and the postures of their respective militaries, coast guards, and fishing fleets. The following sections put forward several potential crisis scenarios that should inform policymakers moving forward. Finally, the concluding section suggests areas that Japan and the United States could explore to improve their ability to deter crises and respond rapidly and decisively if escalation does occur.

The piece was originally published by the AMTI.

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.