A former civilian contractor sentenced to more than seven years in prison after giving classified defense secrets to his girlfriend, a Chinese national, told a judge he would never intentionally harm the United States.

Benjamin Pierce Bishop, 61, who is also a retired Army Reserve lieutenant colonel, said that in an effort to help his girlfriend with research for her doctoral thesis, "I went too far."

U.S. District Judge Leslie E. Kobayashi sentenced Bishop to 87 months in prison Wednesday for communicating national defense information to someone not authorized to receive it, and for keeping classified documents in his home.

Assistant U.S. Attorney Ken Sorenson said the sentence is fair.

"We think it sends a message that individuals who compromise U.S. security, national security, by exposing classified information are going to pay severe sanctions," he said.

Bishop was working for a defense contractor at Camp Smith in 2012 when he disclosed information about a classified conference between the U.S. and South Korea in an email to his 27-year-old girlfriend. The FBI found 10 documents, classified as secret, in a raid of his Makakilo home.

Defense lawyer Birney Bervar said there is no evidence that Bishop showed the secret documents to his girlfriend or that she worked for the Chinese government.

"He made an error, a serious error, in judgment over the love of a woman," Bervar said.

Kobayashi told Bishop that whatever his motive, he cannot be trusted.

The government did not charge Bishop with espionage; there were no allegations that he disclosed the information to harm the U.S. or to benefit a foreign government.

Sorenson said the woman used her romantic relationship with Bishop to collect valuable classified defense information, but questions why she did it.

"Was she collecting for herself or were there other influences?" he said.

Bervar said Bishop’s girlfriend was attending an American university on a Fulbright scholarship. He said she has since returned to China.

Bishop told Kobayashi he met the woman in 2011 at a conference for academics from around the world. All of the academics were graduate students and few had military experience, so he offered to teach them.

Bervar said he thinks Bishop would have received a lighter sentence had he not sent the woman a birthday card and a love letter when he was on release at a halfway house last year. One of the conditions of his release prohibited him from having contact with her.