Late last week, President Trump pardoned two service members and reversed the demotion of a third, each of whom was accused of war crimes. The details of the crimes were different, but the cases shared a common theme: The men were accused of killing civilians or prisoners outside the zone of combat, in violation of the laws of war.

The pardons, made over the objections of the Pentagon, suggest that Trump holds a dangerous, obsolete view of warfare — one that had fallen into disrepute after the horrors of World War II. His actions suggest that he believes in “total war,” in which warfare is conducted not only by professional soldiers but also by entire societies, including their civilians.

The slaughter of the 1940s, in which civilians bore the brunt of much military force, notably through aerial bombings, led nations to recommit themselves to vigorous enforcement of rules on the conduct of war — rules that drew sharp distinctions between combatants and noncombatants, protecting the latter. The goal was to avoid total war at all costs and to ensure that professional soldiers bore the brunt of war’s horror. Trump apparently rejects the combatant-noncombatant distinction as a pointless quibble. Yet such a stance could have dangerous implications, including for both U.S. soldiers and American civilians.

Through the 19th and early 20th centuries, war had been moving steadily in the direction of total war. For example, during the Napoleonic Wars in the early 1800s, militaries used strategies designed to demoralize civilians so they would pressure their leaders for peace. Cities were burned, food sources destroyed.

World War I was no better. When the Germans invaded Belgium in 1914, they massacred civilians and looted the town of Louvain. The rest of the continent suffered a refugee crisis as millions of civilians on both sides were displaced during the fighting. The logical culmination of total war came in World War II with the Holocaust, the strategic bombing of cities as a tactic of demoralization, and the dropping of the atomic bomb.

The rules codified after World War II, however, harked to codes that first rose to prominence during the medieval period. Under “chivalric” codes, warfare was conducted by knights who engaged in battle with one another according to customs or norms of honor. It was considered dishonorable to fight people outside of the circle of those designated to bear arms.

After World War II, the chivalric notion of warfare came to be embodied in international treaties like the Geneva Conventions and domestic statutes like the Uniform Code of Military Justice — which formed the basis for the prosecutions in the three cases into which the president inserted himself. These laws ensure that the burdens of war fall almost exclusively on professional soldiers, who are granted legal immunity to kill enemy soldiers; in turn, they open themselves up to the reciprocal risk of getting killed by the enemy.

Trump’s pardons each involved alleged crimes committed by U.S. soldiers against individuals hors de combat, a technical legal term meaning individuals who are “outside” of combat.

Army Maj. Mathew L. Golsteyn was charged with murder in the killing of a suspected Taliban bombmaker, known as Rasoul, who was in the process of being released from U.S. custody in Afghanistan in 2010. Golsteyn was initially reprimanded but not charged by the military, but during a later job interview with the CIA, Golsteyn admitted that he had executed the man and burned the body, which caused the military to reopen its investigation. Golsteyn was scheduled to be tried in February.

Former Army 1st Lt. Clint Lorance was convicted in 2013 on two counts of murder for ordering his platoon to open fire on civilians riding a motorcycle in Afghanistan. Members of his platoon testified that the victims did not pose a danger to the platoon, and that Lorance had “repeatedly” targeted unarmed civilians, according to the New York Times. Lorance received 20 years in prison.

Former Chief Petty Officer Edward Gallagher was charged with killing a wounded Islamic State detainee who was being treated by a U.S. medic. Gallagher was accused of executing the prisoner with a knife, although at trial the medic dramatically changed his story and claimed to have killed the prisoner himself, by placing his finger on the man’s breathing tube after the knife injury. Gallagher was acquitted of murder but convicted of posing with the corpse for a photograph, and he received a demotion. Trump reversed the demotion.

Such acts violate the core feature of the “war convention” (as the philosopher Michael Walzer has called it) that evolved out of the chivalric notion of combat: namely, the prohibition on harming civilians and soldiers who are either prisoners of war or wounded and therefore incapable of fighting back. (Civilians can be killed as collateral damage — an exception that can be abused but remains important. To be lawful, the death of civilians must be ancillary to the main goal of attacking soldiers, and unavoidable if that goal is to be achieved.) The man Golsteyn is alleged to have killed had just been released from custody; Lorance’s victims were civilians who, according to the military, had taken no part in combat at all; Gallagher’s victim was grievously injured. All were shielded from military attack under the laws of war.

The chivalric notion of warfare does bring with it some negative consequences. Soldiers are given little legal protection, at least while they are fighting, and can be killed in large numbers. These rules of war do not yet create any protections for soldiers who are technologically outmatched, and slaughtered as a result, or unwillingly conscripted into service. And some scholars, such as historian Samuel Moyn, have argued in good faith that our collective obsession with “humane” warfare has crowded out legal prohibitions against starting wars in the first place, ultimately leading to more casualties in the long run.

You would think it would be the professional military that would have the greatest misgivings about the chivalric code, since the military bears the greatest burdens under its rules. But the truth is just the opposite. In the three cases in which Trump granted pardons, military (not civilian) prosecutors worked hard to investigate and prosecute their own service members. Platoon members horrified by conduct they witnessed testified against the defendants.

The White House styled the pardons as an exercise in mercy: a form of sovereign grace that has inspired Trump to issue many pardons over the past three years. (The White House said in a statement that the president is “ultimately responsible that the law is enforced, and when appropriate, that mercy is granted.”) But by issuing the pardons, Trump appears to have rejected the chivalric code of warfare and embraced an ethos of total war without legal restrictions.

The Pentagon recognizes that maintaining unit discipline, respect for rules of engagement and compliance with the law of war is important for protecting the United States. If the chivalric code breaks down and legal restrictions evaporate, there will be no grounds for objection when U.S. service members and civilians fall victim to unrestrained killing and brutality. In total war, civilians on both sides always lose.