China’s aggression is pushing the South China Sea to a boiling point. Beijing’s massive island-building project is militarizing the territorial disputes, changing the territorial status quo and shifting the region’s balance of power. The U.S. response has been reactive, rhetorical and confused.

To stop and reverse Chinese expansion, the U.S. needs a bold and comprehensive strategy. So far, Washington’s approach has consisted of strong remonstrations that call upon China to respect “norms,” exercises of military power in…