The Philippines filed an arbitration case Sunday with the United Nations over China's growing assertiveness in the South China Sea, raising the ante in a long-running dispute over who owns what in the strategic, energy-rich waters.

Manila has been preparing for months to file its challenge to China's claim to control everything within a broad expanse of the sea delineated by its so-called "nine-dash line." The Philippines' submission is nearly 4,000 pages long, includes more than 40 maps and is aimed at countering...