In one of the many frank exchanges U.S. Defense Secretary Chuck Hagel had in China this week, Gen. Fan Changlong told him how one of his uncles died as a slave in a Japanese mine during World War II.

Fan, deputy head of China's powerful Central Military Commission, spoke about the lessons of history, signaling Beijing's concern that the U.S. is siding with Japan against China.

Hagel replied by saying his own father had helped fight Japanese forces during the war. "The secretary made it very clear that we should be informed by history but not driven by it," a U.S. official said in recounting Tuesday's conversation, which he described as terse.