Territorial Disputes in the South China Sea

Territorial Disputes in the South China Sea

An armed confrontation in the South China Sea between China and one or more Southeast Asian claimants to disputed maritime areas

Recent Developments

Territorial and jurisdictional disputes in the South China Sea continue to strain relationships between China and other countries in Southeast Asia and risk escalation into a military clash. The United States has sought to uphold freedom of navigation and support other nations in Southeast Asia that have been affected by China’s assertive territorial claims and land reclamation efforts. In the fall of 2015, the United States signaled that it will challenge China’s assertion of sovereignty over disputed territory by flying military aircraft and deploying ships near some of the islands. 

In recent years, satellite imagery has shown China’s increased efforts to reclaim land in the South China Sea by physically increasing the size of islands or creating altogether new islands. In addition to piling sand onto existing reefs, China has constructed ports, military installations, and airstrips—particularly in the Spratly Islands. 


China’s sweeping claims of sovereignty over the sea—and the sea’s alleged 11 billion barrels of untapped oil and 190 trillion cubic feet of natural gas—have antagonized competing claimants Malaysia, Vietnam, Brunei, Taiwan, Indonesia, and the Philippines. As early as the 1970s, countries began to claim as their own islands and various zones in the South China Sea such as the Spratly islands, which may possess rich natural resources and fishing areas.

China maintains that under international law, foreign militaries are not able to conduct intelligence gathering activities, such as reconnaissance flights, in its exclusive economic zone (EEZ). According to the United States, countries should have freedom of navigation through EEZs in the sea and are not required to notify claimants of military activities. China’s claims threaten sea lines of communication, which are important maritime passages that facilitate trade and the movement of naval forces. In response to China’s assertive presence in the disputed territory, Japan sold military ships and equipment to the Philippines and Vietnam in order to improve their maritime security capacity and to deter Chinese aggression.

In recent years, China has built three airstrips on the contested Spratly Islands to extend its presence in disputed waters, and militarized Woody Island by deploying fighter jets, cruise missiles, and a radar system. China has warned its Southeast Asian neighbors against drilling for oil and gas in the contested region, which has disrupted other nations’ oil exploration and seismic survey activities. To challenge China’s claims in international waters, the United States has occasionally deployed destroyer ships on freedom of navigation operations in the South China Sea to promote freedom of passage. Currently, the Permanent Court of Arbitration in The Hague is hearing a claim brought by the Philippines against China, although Beijing refuses to accept the court’s authority.


The United States, which maintains important interests in ensuring freedom of navigation and securing sea lines of communication, has expressed support for an agreement on a binding code of conduct and other confidence-building measures. The United States has a role in preventing military escalation resulting from the territorial dispute. However, Washington’s defense treaty with Manila could draw the United States into a China-Philippines conflict over the substantial natural gas deposits in the disputed Reed Bank or the lucrative fishing grounds of the Scarborough Shoal. A dispute between China and Vietnam over territorial claims could also threaten the military and commercial interests of the United States. The failure of Chinese and Southeast Asian leaders to resolve the disputes by diplomatic means could undermine international laws governing maritime disputes and encourage destabilizing arms buildups.

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