War between the United States and China is not preordained. But tensions are high, especially in the fiercely contested waters of the East and South China seas -- and even further into the Pacific. Communication is the best medicine: the United States should be explicit with what it needs to know about China's behavior in the waters near its coast. Unfortunately, the intentions and supporting doctrine for Beijing's growing naval capabilities are unclear, specifically regarding disputes with China's Exclusive Economic Zone (EEZ).
Most countries, including the United States, agree that territorial waters extend 12 nautical miles from a nation's coastline, while EEZs extend much further -- usually up to 200 nautical miles. There is also consensus that while the United Nations Convention on the Law of the Sea (UNCLOS) established EEZs as a feature of international law and gives coastal states the right to regulate economic activities within them, it does not provide coastal states the right to regulate foreign military activities in their EEZs beyond their 12-nautical-mile territorial waters. However, China and some other countries like North Korea interpret UNCLOS as giving coastal states the right to regulate all economic and foreign military activities within their EEZs.
There are numerous international agreements that regulate interactions at sea. The United States and Soviet Union signed the Incidents at Sea Agreement (INCSEA) in 1972 after Soviet warships collided with a U.S. destroyer. While INCSEA allowed for U.S. and Russian commanders to communicate directly, and ultimately avoid an escalation of force between warships, it really functioned as a stopgap between the 1972 signature and 1977 implementation of the International Regulations for Preventing Collisions at Sea (COLREGS). And while the 2000 Code for Unalerted Encounters at Sea (CUES) is not an international agreement or legally binding, it does offer safety measures and procedures, and a means to limit mutual interference and uncertainty when warships, submarines, public vessels, or naval aircraft are in close proximity.
The fundamental difference of interpretation between China and most of the world exists on parts IV (archipelagic states) and V (EEZ) of the UNCLOS. The disagreement between China and the United States centers on three issues: First, China asserts that military activities in the EEZ are subject to coastal state approval. Second, excessive maritime claims of territorial sovereignty are a significant sticking point between China and many other nations operating in the East China Sea and the South China Sea. And third, China's demarcation line in the South China Sea, commonly referred to as the "nine-dashed line," is nebulous and defined as neither a territorial sea nor EEZ. Beijing appears to purposefully leave this description vague. Until China agrees that its EEZ is not to be treated as territorial waters, COLREGS, CUES, and any INCSEA-like agreement offers only a partial solution to avoiding dangerous interactions on the high seas.