Military intelligence thought Mansur was linked to a recent IED attack which killed two American soldiers, but, lacking evidence to tie him to terrorism after days of questioning, they had to let him go.

Behenna did not find that satisfactory, and his platoon stopped at a bridge for some questioning of their own. With another soldier, Behenna blindfolded Mansur and cut off all his clothes with a knife. They removed his handcuffs. Then Behenna shot him twice, before allegedly ordering the other soldier to use a grenade to disfigure his body. Though he'd claim to have acted in self-defense, Behenna was court-martialed and convicted of unpremeditated murder in a combat zone. He was initially sentenced to 25 years in prison but served only five. He was released on parole in 2014 and, on Monday, granted a full pardon by President Trump.

Legally, Trump is on steady ground here. The Constitution accords the president expansive pardon powers, which is a boon where victimless drug war offenses are concerned. But what Behenna did was far from victimless, and whether Trump can grant him clemency is a very different question from whether he should. This pardon is a knowing wink at war crimes, and, especially in broader context of the Trump administration's callous approach to civilian casualties, sends an alarming message about what U.S. troops may do in battle.