A Japan-China alignment would negate Western naval power against China’s coast.

Evidence

The United States, Europe, Russia, and India have thus become engaged in a truly global struggle against China, Japan, and most of Islam. How would such a war end? Both sides have major nuclear capabilities and clearly if these were brought into more than minimal play, the principal countries on both sides could be substantially destroyed. If mutual deterrence worked, mutual exhaustion might lead to a negotiated armistice, which would not, however, resolve the fundamental issue of Chinese hegemony in East Asia. Alternatively the West could attempt to defeat China through the use of conventional military power. The alignment of Japan with China, however, gives China the protection of an insular cordon sanitaire preventing the United States from using its naval power against the centers of Chinese population and industry along its coast. The alternative is to approach China from the west. — Samuel P. Huntington, The Clash of Civilizations and the…, 884

Categorization

• XREF: Geography as the deciding stranglehold in great-power war echoes Mahan’s sea-power arguments and the naval-strategy chapters already encountered in the Spanish Armada reads.
• QUESTION: Why does Huntington assume Japan would ally with China rather than balance against it, given conventional balance-of-power theory?