Paracel Islands in the context of "Nine-dash line"

The China–Vietnam border is the international boundary between China and Vietnam, consisting of a 1,297 km (806 mi) terrestrial border stretching from the tripoint with Laos in the west to the Gulf of Tonkin coast in the east, and a maritime border in the Gulf of Tonkin and South China Sea.

While disputes over the terrestrial border have been settled with the signing of a land boundary treaty between the two countries, the maritime border is currently undefined due to disputes over the ownership of territorial waters and islands, including the Spratly and Paracel Islands.

Brunei, Indonesia, Malaysia, the Philippines, the People's Republic of China (PRC), Taiwan (Republic of China/ROC), and Vietnam have conflicting island and maritime claims in the South China Sea. The disputes involve the islands, reefs, banks, and other features of the region, including the Spratly Islands, Paracel Islands, Scarborough Shoal, and various boundaries in the Gulf of Tonkin. The waters near the Indonesian Natuna Islands, which some regard as geographically part of the South China Sea, are disputed as well.

An estimated US$3.36 trillion worth of global trade passes through the South China Sea annually, which accounts for a third of the global maritime trade. 80 percent of China's energy imports and 40 percent of China's total trade passes through the South China Sea. Claimant states are interested in retaining or acquiring the rights to fishing stocks, the exploration and potential exploitation of crude oil and natural gas in the seabed of various parts of the South China Sea, and the strategic control of important shipping lanes. Maritime security is also an issue, as the ongoing disputes present challenges for shipping.