Oh said he hoped to publish the statement in two issues of the Philadelphia Daily News, which first raised questions about his description of his military record a week ago.
The story made Oh a prominent target on veterans' Internet message boards. On Tuesday, the local Fraternal Order of Police lodge withdrew its endorsement of Oh.
Oh enlisted as a private in the Army National Guard in 1988 and became a second lieutenant after going through Officer Candidate School.
He joined the 20th Special Forces Group, a unit of the Maryland National Guard, and was activated for about 90 days during Operation Desert Storm in 1991. The Army issued Oh a green beret, he said, but the war ended while the unit was still at Fort Bragg, N.C., and Oh never went overseas.
In 1991, Oh took a three-week assessment course as a potential candidate for Special Forces training, but he was not invited to continue for the six months of required additional training, he said.
"I am aware of the distinctions within the terms Special Forces and Green Beret, but I did not properly maintain them over the years," Oh's statement said. "My carelessness and lack of attention to detail was to my benefit and misleading to the public. It was disrespectful of those Green Berets, soldiers who are Special Forces-qualified. . . . These are men I admire and respect greatly."
Oh offered to return any campaign contributions that people made under the misimpression that he was a Green Beret or Special Forces officer, terms that appeared on his Council campaign websites in 2003, 2007, and this year.
"Though I served in the 20th Special Forces Group, I was none of those things," Oh said. He promised to destroy any misleading campaign literature and check his website to avoid such claims.
"I would not want to win this election with a cloud that I gained votes or money through deceit or vagueness," Oh concluded. "I am proud of my honorable military service to my country. I ask for your forgiveness. I will try to be more attentive, respectful, and clear in all my actions in the future."
Oh, 51, a lawyer, is one of five Republican candidates for Council at-large seats. As the leading vote-getter among the five in the May primary, he was considered a favorite for one of the two seats the GOP is expected to win in November.
Contact staff writer Bob Warner at 215-854-5885 or warnerb@phillynews.com.