What are China’s claims?
China says it has sovereignty over virtually all South China Sea islands and their adjacent waters. It hasn’t defined those waters, but it issued a map that has what is called a nine-dash line that swoops down past Vietnam and the Philippines, and toward Indonesia, encompassing virtually all of the South China Sea. It has also never clearly explained whether the nine-dash line represents a historical or a legal claim – an important distinction under international law. China says its claim won’t hinder commercial vessels from passing through what is one of the world’s most important shipping routes, but it says foreign military ships shouldn’t conduct operations in the waters it claims.
Read more: http://blogs.wsj.com/briefly/2015/05/27/chinas-claims-in-the-south-china-sea-the-short-answer/