A U.S. federal court in Cincinnati sentenced a Chinese national to 20 years in prison on Wednesday after he was convicted last year of plotting to steal trade secrets from several U.S. aviation and aerospace companies, the Justice Department said. Xu Yanjun, the first Chinese spy extradited to the United States for trial, was convicted in November 2021 by a federal jury on counts of conspiring and attempting to commit economic espionage and trade secret theft. Chinese authorities on Thursday called the allegations against Xu "untrue." Prosecutors had asked for a 25-year sentence to act as a deterrent against similar…