FILE - In this Feb. 5, 1972 file photo, U.S. President Richard Nixon shakes hands with Communist leader Mao Tze-tung during Nixon's historic trip to Communist China. The two countries had no relations whatsoever from 1949, when Mao Zedong‚Äôs communists took power, to 1979, when Jimmy Carter and Deng Xiaoping established diplomatic ties that have endured through good times and tension ever since. The relationship is usually cordial, but the long game is one of unease: China has long believed the United States is trying to contain it, and Washington views Beijing‚Äôs economic heft and increasing presence on the world stage as a strategic and economic threat. (AP Photo/File)