In a single, surprise tweet, President Trump introduced millions of Americans to Army Maj. Mathew L. Golsteyn, a former Special Forces officer who faces a murder charge in the death of a suspected Taliban bombmaker. 

The Army notified the soldier last week that he will face prosecution after a years-long investigation of his actions in one of the largest battles of the Afghanistan War.

The probe was launched in October 2011, after Golsteyn confessed during a CIA job interview that he killed the Afghan in February 2010 because he worried the man would kill U.S. troops, according to Army documents. Golsteyn’s family and attorney have disputed an Army investigator’s description of his statements, which came during a polygraph test.

Golsteyn’s wife, Julie, appeared on “Fox & Friends” on Sunday on his behalf, arguing that her husband has been “ripped apart by his own government” and that they are “waiting for someone to do the right thing.” Minutes later, Trump promised on Twitter that he will review the case, and called Golsteyn a “U.S. Military hero.” White House officials have not answered questions about what the review will include.

The president’s elevation of the case reopened a debate over whether he uses the U.S. military as a tool to feed his political base. Trump also dispatched active-duty troops to the southern U.S. border just before the midterm elections, announced on Twitter that he was banning transgender service members and pressed to hold a massive military parade.

But Trump’s tweet about Golsteyn also brought to boil something deeper after 17 years of war: Long-simmering arguments about what it means to be a war hero and how U.S. troops should behave in combat while guided by rules of warfare that their enemies do not follow.

“A lot of people are taking a side in this without having any idea of the context around it, so it’s very superficial,” said Jason Dempsey, a retired Army officer and Afghanistan veteran who studies the military and society for the Center for a New American Security. “When the tribalism steps in and all of sudden this becomes a red-blue event, or a Fox News event, or a Trump event, it short-circuits anyone even saying, ‘Here’s a complex situation. Maybe I should learn more.’ ”

Golsteyn’s case resembles the plot of a movie thriller. 

The officer, a 2002 graduate of the U.S. Military Academy at West Point, N.Y., commanded a team from 3rd Special Forces Group in the Battle of Marja in February 2010. His actions led to him being labeled as one of its greatest heroes, until the Army decided to punish him.

On Feb. 18, 2010, two Marines working with his team — Sgt. Jeremy R. McQueary, 27, and Lance Cpl. Larry M. Johnson, 19 — were killed when a booby-trapped garage door exploded. U.S. forces searched homes nearby and found the suspected bombmaker, named Rasoul, and bombmaking materials, Golsteyn told the CIA, according to documents first obtained by The Washington Post in 2015.

In the interview, the soldier said U.S. troops detained Rasoul. He also said he crossed paths with an Afghan informant on their base. The informant expressed fear for his life if they let Rasoul go. Golsteyn said he believed that if he let the suspected insurgent go, it could lead to the deaths of more U.S. troops. He said he couldn’t live with that. 

While the timeline isn’t exactly clear, Golsteyn said, with the help of another American he killed the suspected insurgent after they released him and buried him in a shallow grave. He and two other service members dug up the body at night and disposed of it in a burn pit, Golsteyn said, according to military documents.

On Feb. 20, 2010, Golsteyn was involved in separate actions that led to him being decorated for heroism. The Army awarded him a Silver Star after the deployment, crediting him with repeatedly braving enemy fire during a four-hour battle that began with Taliban marksmen opening fire on a lookout point on Golsteyn’s base. The officer launched an ­80-man patrol to find them, slogging through mud and coordinating airstrikes under a barrage of fire.

Army investigators reviewing Golsteyn’s actions interviewed more than a dozen service members, some of whom were offered immunity. The case was closed two years later without criminal charges. The Army, however, revoked his Silver Star, and Golsteyn lost his coveted Special Forces tab and was reassigned to the conventional Army.

In 2015, a panel of officers at Fort Bragg, N.C., reviewed Golsteyn’s actions. It determined it could not substantiate that Golsteyn violated the rules of armed conflict, but found he demonstrated conduct unbecoming of an officer and recommended his separation from the Army.

That could have been the end of the story. But Golsteyn appeared on Fox News in October 2016, admitting to killing a suspected bombmaker. The Army reopened its investigation a month later. An Army spokesman, Lt. Col. Loren Bymer, said investigators have uncovered new information but declined to elaborate, citing the pending legal action.

Members of the Golsteyn family and his attorney, Phillip Stackhouse, have mounted a media blitz in recent days, arguing in television interviews that the Army determined in 2015 that the allegations saying the killing was illegal were not substantiated. They also have pointed out accurately that Trump could pardon Golsteyn at any time, or take charge of the case himself.

“The president is the commander in chief of the armed forces, and he is also a general court-martial convening authority,” said Zach Spilman, an attorney and contributor to the military justice blog CAAFlog. “Those two roles give him the power to take control of any case under military law, including the Golsteyn case.”

Stackhouse said in an interview with The Post that he and the Golsteyns are not attempting to lobby the president through the media. He said they want to correct inaccurate reporting. Golsteyn did not kill a detainee, he said, but a man who had been released.

Then Stackhouse proposed an idea that only could be carried out by Trump.

“The president can issue a pardon in this case today,” he said. “What better time to take action in a case like Matt’s than during the Christmas season?”

Other observers see a strategy taking shape. 

Rachel E. VanLandingham, a military justice expert at Southwestern Law School in Los Angeles, said placing Golsteyn’s case “in the public square” for discussion is “disgusting” and “brilliant.”

“If you think you can play on the president’s desire to throw red meat to his base, go for it,” said VanLandingham, who served as a lawyer in the Air Force. “It’s highly unusual and irregular, but it’s smart.”

Veterans watching the case have clashed, arguing over whether Golsteyn is being unfairly targeted by the Army or lionized by supporters despite an alleged war crime.

Joe Kassabian, who deployed twice to Afghanistan, said he thinks the length of time that the United States has been at war has led to “this explaining away of abhorrent behavior” carried out by U.S. troops. 

“People just saying, ‘He’s at war! What do you expect?’ ” said Kassabian.

He pointed out that the United States was on the other side of the issue 74 years ago this month. On Dec. 17, 1944, 84 American prisoners of war who had surrendered after being surprised by a unit of German soldiers were executed in the Malmedy massacre. 

Sean Parnell, a former captain in the 10th Mountain Division, said he sees the situation differently. In his estimation, the rules of engagement in combat keep U.S. troops from responding when they otherwise would, creating tough judgment calls. 

Parnell recalled a situation in 2006 in which an insurgent infiltrated the Army as a translator and opened fire on his platoon, killing one U.S. soldier and wounding others. Despite there being evidence and surviving witnesses, Parnell said, the military let the man go because of missing paperwork.

“We let this guy back on the battlefield,” Parnell said. “He’s out there right now, and I don’t know if he’s alive or dead 10 years later, but he was allowed to go back out onto the battlefield and potentially go back to killing Americans. That drives me insane.”

VanLandingham, who once served as the chief of international law for U.S. Central Command, said she thinks the polarized response to Golsteyn’s case speaks to something more enduring than present-day politics.

“Human beings like to blame another, and we like to support our troops,” she said. “We’re looking for heroes, and we don’t have that many these days. Maybe our service members are our last heroes.

“That makes thinking that they have done something that they shouldn’t have even harder.”