(Adds contractor has pleaded guilty)
By Jonathan Kaminsky
March 13 (Reuters) - A U.S. defense contractor in Hawaii pleaded guilty on Thursday to charges he passed national defense secrets, including classified information on joint training and planning exercises with South Korea, to a Chinese woman with whom he was romantically involved, prosecutors said.
Benjamin Pierce Bishop, 60, a former U.S. Army officer, was working as a civilian employee of a defense contractor at U.S. Pacific Command in Oahu when he was arrested last year and charged with one count of communicating national defense information to a person not entitled to receive it and one count of willfully retaining documents related to national defense.
He pleaded guilty to those charges in court on Thursday afternoon, Honolulu-based U.S. Attorney Florence T. Nakakuni said in a statement. The charges carry a maximum of 20 years in prison.
"This case once again demonstrates our commitment and unwavering resolve to pursue and prosecute individuals who violate their security oaths and endanger our national security by unlawfully communicating sensitive and damaging classified national defense information to persons who are not entitled to receive it," Nakakuni said.
Bishop's lawyer did not immediately respond to messages seeking comment.
China and the United States, the world's two largest economies, have long engaged in spying against each other, though prosecutors have not said whether they believe the woman, identified in court documents as "Person 1," was working for the Chinese government.
The FBI said in an affidavit filed last year that the pair met in Hawaii at an international military defense conference and that she may have been targeting individuals with access to classified information.
They had been romantically involved since June 2011, with the woman living in the United States on a student visa and without security clearance, the affidavit said.
From May of that year through December 2012, according to the affidavit, Bishop passed national defense secrets to the woman on several occasions, including classified information about nuclear weapons and the planned deployment of U.S. strategic nuclear systems.
Other secrets mentioned in the affidavit included information on the United States' ability to detect foreign governments' low- and medium-range ballistic missiles, and information on the deployment of U.S. early warning radar systems in the Pacific Rim.
Bishop had top secret security clearance since July 2002. A court-authorized search of his home in November found about a dozen individual documents each with classification markings at the secret level, the affidavit said. (Editing by Alex Dobuzinskis and Ken Wills)