China's Maritime Disputes

The East and South China Seas are the scene of escalating territorial disputes between China and its neighbors, including Japan, Vietnam, and the Philippines. The tensions, shaped by China's growing assertiveness, have fueled concerns over armed conflict and raised questions about Washington's security commitments in its strategic rebalance toward the Asia-Pacific region.

We are strongly committed to safeguarding the country's sovereignty and security, and defending our territorial integrity.

Chinese President Xi Jinping

Mapping the Claims

Six countries lay overlapping claims to the East and South China Seas, an area that is rich in hydrocarbons and natural gas and through which trillions of dollars of global trade flow. As it seeks to expand its maritime presence, China has been met by growing assertiveness from regional claimants like Japan, Vietnam, and the Philippines. The increasingly frequent standoffs span from the Diaoyu/Senkaku Islands, on China’s eastern flank, to the long stretch of archipelagos in the South China Sea that comprise hundreds of islets. The U.S. pivot to Asia, involving renewed diplomatic activity and military redeployment, could signal Washington’s heightened role in the disputes, which, if not managed wisely, could turn part of Asia’s maritime regions from thriving trade channels into arenas of conflict.

East and South China Sea Claims


China claims the largest share of territory in the South China Seas, basing its assertions on historical grounds demarcated by a nine-dash line it drew in 1947. It does not adhere to the international protocols set out by the United Nations Convention on the Law of the Sea (UNCLOS), and has clashed militarily with Vietnam and the Philippines over the Paracels and Spratly Islands. It has also resisted attempts to resolve the disputes through UNCLOS or regional body ASEAN, preferring to pursue conflict resolution bilaterally. China’s maritime claims extend to the Diaoyu/Senkaku Islands in the East China Sea, where it has clashed with Japan. Rising nationalism in both countries and a long wartime history have escalated tensions despite highly interconnected economies.


Taiwan, where the Koumintang regime settled after defeat by communists on the mainland in 1949, adheres to the same nine-dash-line claim as China in the South and East China Seas. It currently has a presence on the Spratly and Pratas Islands.


The Philippines claims the Paracel and Spratly Islands based on its EEZ and continental shelf zones. Tensions reached an inflection point with the Chinese occupation of the Spratly’s Mischief Reef in 1994, leading to the first instance of combat between China and an ASEAN member other than Vietnam. Much of Manila’s territorial tension with Beijing centers around competition for resource development, and skirmishes have erupted regularly since March 2011. In early 2013 the Philippines was the first claimant country to launch an arbitration case under UNCLOS against China’s South China Sea claims.


Malaysia claims some islets in the southern Spratlys, and has occupied five of them since 2009. In 1991, it developed a resort and built an airstrip on Swallow Reef to promote tourism, prompting fellow claimants, including the Philippines, Vietnam, Brunei, and China, to protest. It clarified its claims in 2009 with the joint Vietnamese-Malaysian submission to UNCLOS on the limits of the continental shelf, and maintains a less confrontational relationship with China than other claimants.


While Brunei has not made any formal claims or engaged in any confrontation with other claimants, it lays claim to the Louisa Reef and Rifleman Bank, two formations in the southern Spratlys, based on its EEZ. Brunei’s territorial claims overlap those of neighboring Malaysia, and juts into those of China, Vietnam, and the Philippines. It does not occupy any of the islands, nor does it have a military presence in the South China Sea.


Japan claims it annexed what it calls the Senkaku Islands in 1895. It retained residual sovereignty over the islands after the Treaty of San Francisco in 1951, and the United States returned full control of the territory to Tokyo after the Okinawa Reversion Treaty in 1971. Japan views the Treaty of San Francisco and this reversion agreement as validation of its sovereignty over the islands.


Vietnam has been one of the most vocal claimants in the South China Sea dispute. It claims the Spratly and Paracel Islands based on its EEZ and continental shelf zones, and joined Malaysia in May 2009 in a joint submission of territorial claims in the South China Sea to UNCLOS. Vietnam fought China in 1947 over the Paracels, which China occupied, and again in 1988 when China’s navy sank three Vietnamese vessels, killing seventy-four Vietnamese sailors on the Johnson Reef in the Spratlys. The confrontation marks China’s first armed conflict over the Spratlys, and one of the most serious military clashes in the South China Sea.

Provocations against Japan’s sovereign sea and land are continuing, but they must not be tolerated.

Japanese prime minister Shinzo Abe

Historical Context

China’s maritime disputes span centuries. The tug-of-war over sovereignty of the Diaoyu/Senkakus in the East China Sea can be traced to the Sino-Japanese War of 1894, while Japan’s defeat in World War II and Cold War geopolitics added complexity to claims over the islands. The fight over overlapping exclusive economic zones in the South China Sea has an equally complex chronology of events steeped in the turmoil of Southeast Asian history. Globalization—including extensive free trade pacts between claimants—and recent developments like the U.S. “pivot” to Asia have further connected the two disputes. As China’s economic ascent facilitates growing military capabilities and assertiveness in both seas, other regional players are also experiencing their own rise in nationalism and military capability, and have exhibited greater willingness to stake territorial claims.

To be realistic about it, how does one push around a superpower?

Philippine President Benigno Aquino

By the Numbers

Vietnam will do what it can to join other regional countries in consolidating peace and stability in the region.

Vietnamese Prime Minister Nguyen Tan Dung

Power Projection

In recent years, China has undertaken drastic efforts to dredge and reclaim thousands of square feet in the South China Sea. Its construction of artificial islands and infrastructure, such as  runways, support buildings, loading piers, and possible satellite communication antennas, has prompted its neighbors and the United States to question whether they are strictly for civilian purposes, as claimed by the government. China’s land development has profound security implications. The potential to deploy aircraft, missiles, and missile defense systems to any of its constructed islands vastly boosts China’s power projection, extending its operational range south and east by as much as 1,000 kilometers (620 miles). The map below illustrates a hypothetical power projection if Chinese military capabilities were established at Subi Reef.

China's Potential Power Projection

Subi Reef

Ranges are based on the hypothetical deployment of military capabilities to Subi Reef in the northern Spratlys, a feature claimed by China, the Philippines, Taiwan, and Vietnam.

China's Island Building

China’s highest rate of island development activity is taking place on the Paracel and Spratly Island chains. Beijing has reclaimed more than 2,900 acres (PDF) since December 2013, more land than all other claimants combined in the past forty years, according to a U.S. Defense Department report. Satellite imagery has shown unprecedented activity from China on Subi Reef and Fiery Cross Reef in the Spratlys, including the possible construction of helipads, airstrips, piers, and radar and surveillance structures. In addition to China, the Spratlys are claimed by Malaysia, the Philippines, Vietnam, and Taiwan. Experts say that China’s artificial island building and infrastructure construction are increasing its potential power projection capabilities in the region.

Subi Reef

Fiery Cross Reef

The South China Sea issue is not just about competing claims; it’s about peace and stability in the region.

ASEAN Secretary General Le Luong Minh

Policy Options

Thousands of vessels, from fishing boats to coastal patrols and naval ships, ply the East and South China Sea waters. Increased use of the contested waters by China and its neighbors heighten the risk that miscalculations by sea captains or political leaders could trigger an armed conflict, which the United States could be drawn into through its military commitments to allies Japan and the Philippines. Policy experts believe that a crisis management system for the region is crucial.


A range of preventive measures could ease regional tensions and de-escalate the risk of military conflict. Experts including Elizabeth Economy, Sheila Smith, Joshua Kurlantzick, and Simon Tay weigh the options.

Resource Sharing

Claimants in both the South China Sea and East China Sea could cooperate on the development of resources (PDF), including fisheries, petroleum, and gas. A resource-sharing agreement could include bilateral patrolling mechanisms, which would deter potential sources of conflict like illegal fishing and skirmishes arising from oil and gas exploration. More collaborations in the mold of joint fishery deals like those between China and Vietnam and Japan and Taiwan could mitigate risk by sharing economic benefits.

Military-to-Military Communication

Increased dialogue between military forces has the potential to reduce the risk of conflict escalation. Communication mechanisms like military hotlines to manage maritime emergencies, similar to the ones set up by China and Japan, China and Vietnam, and China and ASEAN, could be established among all claimants. These hotline systems would connect leaders in the event of a crisis that could arise from mishaps, such as naval maneuvers misinterpreted by captains of merchant vessels or fishermen. Lastly, joint naval exercises, such as those proposed by Beijing in October 2015, could support greater military transparency and help develop shared rules of the road.

Building a Multilateral Framework

The development of a multilateral, binding code of conduct between China and ASEAN countries is often cited as a way of easing territorial disputes in the South China Sea. The parties have already agreed upon multilateral risk reduction and confidence-building measures in the 2002 Declaration on the Conduct of Parties in the South China Sea, but none have adhered to its provisions or implemented its trust-building proposals. While China has historically preferred to handle all disputes bilaterally, ongoing consultations between Beijing and ASEAN still hold some promise for reinvigorating a multilateral framework toward greater cooperation and conflict resolution. However, given differences among ASEAN members vis-à-vis China and China's preference to settle matters bilaterally, it is uncertain whether progress can be made.

International Arbitration

Bringing territorial disputes to an international legal body presents another means of conflict mitigation. The International Court of Justice and the International Tribunal for the Law of the Sea are two forums where claimants can file submissions for settlement. In July 2013, a UN tribunal was convened in The Hague to discuss an arbitration case filed by the Philippine government contesting the legality of China’s territorial claims in the South China Sea. The court ruled in October 2015 that it has jurisdiction to hear some of the claims filed against China, and a ruling is pending. An outside organization or mediator could also be called upon to resolve the disagreement, although the prospect for success in these cases is slim given China’s likely opposition.


In the event military conflict erupts, policy experts including Elizabeth Economy, Sheila Smith, and Shen Dingli outline a few immediate options facing the countries involved.


Escalatory actions would likely trigger ramped up diplomacy. The United States could initially serve in a mediation role in the event of crisis erupting in either sea. In the South China Sea, mediation could also come from ASEAN or a trusted, neutral actor within the region like Singapore. Parties could also call for an emergency session of the UN Security Council to negotiate a cease-fire, although China’s permanent seat on the Council could limit the effectiveness of this option. In the East China Sea, bilateral management of the dispute is the likely first option, with Beijing and Tokyo sitting down to negotiate a common guideline for handling the conflict and preventing its escalation. Chinese and Japanese officials made a breakthrough to ease tension in November 2014, issuing a joint four-point outline to improve Beijing-Tokyo relations.


Despite extensive trade ties, the parties to the dispute could respond to a rise in tensions by imposing economic sanctions. In response to a Chinese action, for instance, the United States could sanction financial transactions, the movement of some goods and services, and even travel between the two countries. In retaliation, Beijing could bar U.S. exports and cut back on its extensive holdings of U.S. Treasuries. Claimants could also manipulate exports and relaunch boycotts of goods. Signals of such a response have already been seen: in 2012 Chinese protesters launched a wave of boycotts of Japanese-made products. Japan also accused China of halting exports of rare earth minerals after a territorial spat in 2010—a charge Beijing denied—causing a commodities crisis for resource-dependent Japan.


If confrontation were to involve Japan in the East China Sea or the Philippines in the South China Sea, the United States would be obligated to consider military action under defense treaties. Experts note that Washington's defense commitments to Tokyo are stronger than those to Manila. Under its treaty obligations, the United States would have to defend Japan in the case of an armed attack; the U.S.-Philippine treaty holds both nations accountable for mutual support in the event of an “armed attack in the Pacific Area on either of the Parties.” Military action would represent a last resort, and would depend on the scale and circumstances of the escalation. In the event of armed conflict breaking out between China and Japan, the United States could also use crisis communication mechanisms outlined in the U.S.-China Military Maritime Consultative Agreement (PDF) to encourage a stand-down of forces and facilitate communication between Tokyo and Beijing. Verbal declarations that communicate the seriousness of the dispute and convey support for an ally, as well as offers of military assistance, can also serve as essential “coercive de-escalation” measures during a crisis.

In the South China Sea, Washington has protested against Beijing’s extensive land reclamation efforts, warning that island development and a military buildup could lead to regional conflict. The U.S. military deployed surveillance aircraft over the Chinese-built artificial islands in 2015 and sent warships to sail within 12 nautical miles of disputed features in the Paracel and Spratly island chains to emphasize the importance of freedom of navigation in the contested waters. These operations, intended to challenge China’s maritime claims, are expected to expand in scope and have received support from U.S. regional allies.

This is the future we seek in the Asia-Pacific—security, prosperity and dignity for all ... let there be no doubt: in the Asia-Pacific in the twenty-first century, the United States of America is all in.

U.S. President Barack Obama