These political acts have been matched by military and economic expansion. On July 22, China’s Central Military Commission announced that it would deploy a garrison of soldiers to guard the islands in the area. On July 31, it announced a new policy of “regular combat-readiness patrols” in the South China Sea. And China has now begun offering oil exploration rights in locations recognized by the international community as within Vietnam’s exclusive economic zone.

For all practical purposes China has unilaterally decided to annex an area that extends eastward from the East Asian mainland as far as the Philippines, and nearly as far south as the Strait of Malacca. China’s new “prefecture” is nearly twice as large as the combined land masses of Vietnam, South Korea, Japan and the Philippines. Its “legislators” will directly report to the central government…

History teaches us that when unilateral acts of aggression go unanswered, the bad news never gets better with age. Nowhere is this cycle more apparent than in the alternating power shifts in East Asia. As historian Barbara Tuchman noted in her biography of U.S. Army Gen. Joseph Stillwell, it was China’s plea for U.S. and League of Nations support that went unanswered following Japan’s 1931 invasion of Manchuria, a neglect that “brewed the acid of appeasement that . . . opened the decade of descent to war” in Asia and beyond.

While America’s attention is distracted by the presidential campaign, all of East Asia is watching what the U.S. will do about Chinese actions in the South China Sea. They know a test when they see one.