evidence: China now is attempting to expand its control to the southernmost extent of its nine-dash-line claim in the South China Sea, in waters ever closer to Indonesian and Malaysian shores. This area of the South China Sea, spanning from Indonesia’s Natuna Islands to the South Luconia Shoals, has greater strategic importance than the Spratly or Paracel Island chains farther to the north. Whereas the Spratlys have for centuries been regarded as "dangerous ground" and commercial mariners have avoided them, the vital sea lines of communication (SLOCs) connecting the Pacific and Indian Oceans flow through this part of the southern South China Sea. Therefore, these areas are far more vital to international commerce and navigation than the dangerous grounds closer to China’s Spratly Islands outposts. [...] These vessels include two new classes of nuclear submarines-the advanced Song-class diesel submarines and the Yuan class of diesel boats which, according to some reports, was a surprise for U.S. intelligence. Above and beyond this ambitious naval construction program, the People's Republic of China (PRC) received during 2005-06 an additional eight formidable Kilo-class submarines (and associated weaponry), which were purchased in 2002, to add to the four it already operated. A new nuclear submarine base on Hainan Island may well herald a new era of more extended Chinese submarine operations.