The 39-year-old officer, whose address is given as the proving ground, is charged with two felony counts of sexually abusing a minor, perverted practice and two counts of third-degree sex offense.
The Aegis is not disclosing the officer's name because of his relationship to the alleged victims.
The Tennessee native has been a platoon leader in Iraq and worked as a military intelligence specialist before recently being transferred to APG from Georgia to work as an acquisitions officer in the Army's research lab, public defender Bruce Andres said at a bail review in Harford County District Court in Bel Air Wednesday afternoon.
"He has been serving with the Army for 22 years, with the reserves and also the National Guard," Andres said, adding the defendant has four years before retirement from the Army.
Andres said the officer is being treated for post-traumatic stress disorder.
The defendant allegedly abused two young children, assistant state's attorney Christopher Tabone said, adding the Sheriff's Office had to respond because he was threatening suicide.
Police charging documents say the defendant forced his victims to perform sex acts on him.
"What concerns me greatly is he was smart enough to be a major in the U.S. Army," Tabone said. "He is a major danger to himself, his wife and children, and he is a huge flight risk."
Judge Mimi Cooper ordered the officer held on no bond and noted he is on suicide watch. She also ordered him to have no contact with any children under the age of 18.
"I make a finding that you are an extremely high risk of flight and an extremely high danger to the rest of us, particularly anyone under 18," she said to the defendant, who appeared from the jail via closed circuit television.
Andres said the officer graduated from Cannon County High School in Tennessee, earned a bachelor's degree in criminal justice from Middle Tennessee State University and also a master's degree in project management.
"He has a very, very honorable service record as an armed forces officer," the public defender said.