A five-member military review board upheld Greene's involuntary discharge in July 2006, The Post and Courier of Charleston reported. A year later, Greene joined the Army National Guard, in which he served about six months before joining the Army.
"We've already gone through that. There is no need to bring something up over again," Greene told said. "It's old news. You should just leave it alone."
Under the Uniform Code of Military Justice, enlisted personnel can receive an honorable discharge, a general discharge under honorable conditions or a general discharge under conditions other than honorable.
Greene received a general discharge under honorable conditions, a step below a full honorable discharge, according to documents released in July to The Associated Press from the National Personnel Records Center.
Greene won a surprise victory in the June 8 Democratic primary when he handily defeated a former lawmaker. He has been indicted on a felony obscenity charge accusing him of showing Internet porn to a female University of South Carolina student.
Greene often mentions his 13 years of military service, saying he came up with the idea to seek political office while serving in Korea.
The veteran has also refused to go into detail, merely saying he won numerous decorations and left the military honorably but involuntarily.
In July, the AP reported Greene received adequate marks for performing basic tasks and complying with training requirements. Reviewers marked Greene as an ineffective leader who lacked organization and received disciplinary actions for failing to perform his duties.
Greene was also written up for posting sensitive information on a military Internet server, according to the records uncovered in July. They show he was kept at Shaw Air Force Base while the rest of his unit deployed after leadership "recognized his inability to contribute to the wartime mission."