It is no secret that the South China Sea is an area of conflict and controversy, but understanding the interests and role of the United States in that region is not intuitive. The situation centers on competing territorial claims by China, Vietnam, Taiwan, Brunei, the Philippines and Malaysia over several sets of islands. Attempts by these nations to control the disputed territories have become increasingly intense, bordering on violence, and vessels have narrowly avoided collision in recent displays of hostility. As the BBC reported on 15 October 2014, it even appears as though the United States is practicing for war with China in case the conflict heats up. Most articles on the subject explain that what is at stake is a mix of territory, fishing rights, mineral rights and control of shipping lanes. It is understandable why, given the economic value of those rights, the states competing over the claims would be willing to resort to violence, especially since a number of the claims involve emotionally charged historical ties and concern national identity and pride. But why would the US, which is already facing potentially extensive engagements in Eastern Europe and the Middle East, be at all inclined to enter a naval war with one of its closest peers in terms of economic resources and military might? The full answer involves a number of different justifications, but one of the most important ones has received very little attention. As it requires a nuanced understanding of international maritime law, most articles and reports on this simmering conflict in Southeast Asia have failed to even mention it. Simply put, if China gains the disputed territory, it may be able to block access of US Naval vessels and aircraft through most of the South China Sea.