HONOLULU (AP) — A former civilian defense contractor in Hawaii on Thursday pleaded guilty to charges he divulged military secrets to his Chinese girlfriend and kept classified documents at his suburban Honolulu home.

Benjamin Bishop, 60, told the court he mentioned a classified conference between U.S. and South Korean officials while responding to an email from the 28-year-old girlfriend.

He admitted to keeping classified documents at his home, including ones outlining the U.S. Pentagon's China strategy and the U.S. military's force posture in Asia and the Pacific. He told U.S. Magistrate Judge Kevin Chang he didn't show the documents to anyone, but they shouldn't have been at his house.

Bishop faces up to 10 years in prison on each of two counts. Sentencing has been scheduled for June 26.

Bishop didn't speak at the hearing beyond brief remarks outlining the nature of his offenses. He wore a white prison jumpsuit. His wrists and legs were shackled in chains.

Bishop's attorney, Birney Bervar, told reporters after the hearing the girlfriend was a graduate student in the field of Bishop's expertise. He said they developed a friendship that became romantic.

"He was helping her with her graduate studies and her thesis," Bervar said. Bishop took some documents home "in order to educate himself to help her. He did not give her any documents. He did not show her any classified information."

As for the email, Bishop briefly wrote about a conference that was classified, Bervar said.

"He said too much in an email to her," Bervar said. He reiterated the two were in love and the case was about love and not spying.

Assistant U.S. Attorney Ken Sorenson, the prosecutor in the case, said any time classified information is given to someone without a security clearance, the U.S. loses control of that information.

"Because it could have been about love or because it could have been his girlfriend doesn't mean it wasn't damaging or doesn't mean she may or may not have been affiliated with somebody else," Sorenson said. "We don't know that."

Authorities have not released the girlfriend's identity or whereabouts, or said publicly whether they believe she was working for the Chinese government. She was a Chinese national and living in the United States as a student on a J-1 visa, according to the FBI.

An affidavit filed by the FBI last year alleged that she may have attended an international defense conference in Hawaii specifically to target people like Bishop who had access to classified information. The affidavit said they met at the conference and then started a romantic relationship in 2011.

Bishop worked in the field of cyber defense at U.S. Pacific Command from May 2011 until his arrest. Before that, he helped develop Pacific Command strategy and policy. He retired from the U.S. Army Reserve as a lieutenant colonel last August.

Bishop was arrested nearly one year ago at Pacific Command headquarters. He has spent much of the past year in solitary confinement at the federal detention center in Honolulu, Bervar said.

A judge allowed him to move to a halfway house last June while awaiting trial. But he was ordered him back to jail in December after he violated the terms of his release by emailing his girlfriend and writing her a letter.

The specific counts he pleaded guilty to are communicating national defense information to a person not entitled to receive it and one count of unlawfully retaining national defense documents and plans.