CITING an escalating dispute over islands in the East China Sea, The Economist warned last week that “China and Japan are sliding toward war.” That assessment may be too alarmist, but the tensions have bolstered the efforts of some American analysts who have urged a policy to “contain” China. During a recent visit to China, I was struck by how many Chinese officials believe such a policy is already in place and is the central purpose of President Obama’s “pivot” toward Asia. “The pivot is a very stupid choice,” Jin Canrong, a professor of international relations, declared publicly. “The United States has achieved nothing and only annoyed China. China can’t be contained,” he added.