FILE - Framed in the opening of a wall, then U.S. President Richard Nixon and then Chinese Premier Zhou Enlai walks past as they tour Hangzhou in the eastern Chinese province of Zhejiang on Feb. 26, 1972. At the height of the Cold War, U.S. President Richard Nixon flew into communist China's center of power for a visit that over time would transform U.S.-China relations and China's position in the world in ways that were unimaginable at the time. (AP Photo, File)