A cold war is already under way. The question is whether Washington can deter Beijing from initiating a hot one.

President Xi Jinping declared in July that those who get in the way of China’s ascent will have their “heads bashed bloody against a Great Wall of steel.” The People’s Liberation Army Navy is churning out ships at a rate not seen since World War II, as Beijing issues threats against Taiwan and other neighbors. Top Pentagon officials have warned that China could start a military conflict in the