A judge has revoked bail for a defense contractor accused of giving military secrets to his Chinese girlfriend because he sent her a letter and email.

U.S. District Magistrate Judge Kevin Chang Thursday ordered Benjamin Bishop back to federal detention while he awaits trial.

Defense attorney Birney Bervar says Bishop was sending the girlfriend love letters.

Bervar says Bishop asked another resident of the halfway house where he has been living to send her the letter and set up an email account so he could contact her.

U.S. District Court Judge Leslie Kobayashi ruled Bishop could stay at the halfway house but she imposed conditions designed to prevent him from contacting the girlfriend.

Investigators say Bishop gave his girlfriend secrets about nuclear weapons, missile defense and other issues.