China has warned the United States that it would retaliate if Washington presses on with charges against five Chinese military officers accused of hacking into American companies to steal trade secrets, state media said on Tuesday. The warning from an unnamed State Internet Information Office spokesman came hours after the United States charged the five Chinese, accusing them of hacking into American nuclear, metal and solar companies to steal trade secrets. It was the first criminal hacking charge that the United States has filed against specific foreign officials, and follows a steady increase in public criticism and private confrontation, including at a summit last year between U.S. President Barack Obama and Chinese President Xi Jinping. The indictment is likely to further roil relations between China and the United States.