Trump's statement alone could complicate the military's prosecution of Golsteyn.
The President, as commander in chief, is expected in the military justice system to not make statements that could influence open cases. Doing so is considered unlawful command influence and can result in cases being thrown out.
Golsteyn's lawyer, Phillip Stackhouse, has disputed that Golsteyn's statement to the CIA was characterised accurately by the Army.
The service launched an investigation into Golsteyn after the CIA alerted them to his job interview, but closed it without charging him. But the case was reopened in 2016, after Golsteyn said during a Fox News interview that he had killed a bombmaker, who had been held as a detainee, out of fear that the bombmaker would target Afghans helping US troops if he were let go.
Golsteyn, a 2002 graduate of the US Military Academy at West Point, New York, was lauded for his performance in Afghanistan as the commander of a team from 3rd Special Forces Group in the Battle of Marja. About 15,000 coalition troops fought to take back a poppy-laden section of Helmand province that was controlled by the Taliban and laced with explosives.
On February 20, 2010, Golsteyn coordinated numerous airstrikes and repeatedly braved enemy fire after launching a mission to kill a Taliban sniper who nearly hit a nearby Marine, according to a military summary of his actions.
He was later awarded the Silver Star for valour, and the Army was considering upgrading the award to the Distinguished Service Cross - one step down from the Medal of Honour - when the allegations against Golsteyn emerged.
The accusations centre on actions that occurred two days earlier.
Two Marines - Sergeant Jeremy McQueary, 27, and Lance Corporal Larry Johnson, 19 - were killed and others were wounded by a garage door that was booby trapped with explosives, prompting a search of nearby homes in which Golsteyn's unit found bombmaking materials and a suspected bombmaker, according to the results of an investigation released to the Washington Post through the Freedom of Information Act in 2015.
Golsteyn later recounted during his CIA job interview that the US troops detained the man and brought him back to their base. While detained, the suspected bombmaker unexpectedly crossed paths with an Afghan tribal leader with whom Golsteyn's team was working. When the leader expressed fear for his life, Golsteyn said, he grew concerned about the consequences of letting the suspected bombmaker go, according to Army documents.
"CPT Golsteyn related there had been countless times when he detained someone and sent that person to a detention facility only to see that same person shooting at his unit weeks later," an Army investigator's summary of Golsteyn's polygraph test said.
"CPT Golsteyn stated he had no qualms about what he did because he couldn't have lived with himself if [the suspected bombmaker] killed another Soldier or Marine."
The Army dropped Golsteyn from the Special Forces and stripped him of the Silver Star.
The service accused him in a June 2015 administrative hearing of violating the law of armed conflict, but a panel of officers determined that was unsubstantiated. It instead recommended separating him from the military for conduct unbecoming an officer with a general discharge under honourable conditions.
