A longtime Foreign Service officer at the State Department, who until recently was a ranking official on East Asian affairs, was arrested on Wednesday and charged with concealing a trip to Taiwan, and is suspected of improperly passing documents to Taiwanese intelligence agents, law enforcement and intelligence officials said. The diplomat, Donald W. Keyser, appeared in federal court in Alexandria, Va., and was charged with making a false statement to the Federal Bureau of Investigation in a government background check. A career foreign service officer, Mr. Keyser was a top advisor on China to Secretary of State Colin L. Powell before resigning abruptly several weeks ago in the face of accusations that he had passed information to the Taiwanese, officials said.Full Story