Once again, disturbing images are surfacing from the war in Iraq, this time of a young Marine shooting a wounded Iraqi prisoner in Fallujah. The soldier in question has been removed from duty and may face a court martial. U.S. military and Iraqi officials have decried the incident.

This sort of act is nothing new in war. Unarmed, or seemingly unarmed, people have been killed before and will be killed again by soldiers making split-second decisions under almost inconceivable stress. This event, however, and the reactions to it, illustrate exactly why the United States may be forced to follow Vermont Senator George D. Aiken’s advice on ending the war in Vietnam — just declare victory in Iraq and withdraw.

In the past, the United States has tried to apply the principle of “civilized warfare.” After the World War II, we tried German and Japanese officers for mistreating prisoners of war and civilians. We were one of the first nations to sign the 1949 Geneva Conventions on the conduct of war. When the Viet Cong in the 1970s and the Iraqis in 1990 paraded captured Americans in front of television cameras, the nation was appalled. Despite urging from some quarters, the United States has not used nuclear weapons since 1945, and in recent bombing campaigns one of the goals of the Air Force has been to minimize civilian casualties.

Still, there has been a dark side to our conduct. While the Allies tried and hanged the architects of the German concentration camps in the 1940s, charges that U.S. soldiers starved and beat German POWs were generally ignored until the last decades of the 20th century. Tales of Americans committing atrocities in Korea have persisted for decades. While it is reasonable to assume that most of these accounts are North Korean propaganda, the Pentagon reluctantly admitted in 2001 that U.S. forces had killed refugees at No Gun Ri in 1950. These stories did not appear in textbooks or popular histories, and when they were brought up in public discourse, they were dismissed as anti-American naysaying.

With the Vietnam War, this attitude started to change. The army publicly charged and convicted Lt. William Calley of killing 22 villagers at My Lai. He may have become a sort of folk hero during his trial and was later paroled, but the taboo against discussing the less-than-honorable actions of U.S. soldiers had been broken. Stories of necklaces made of Viet Cong ears, burning villages and American-caused civilian casualties became the fodder of the nightly news. That is where they remain.

The United States puts itself forward as a force of civilization and justice in the world. Our soldiers are supposed to behave honorably, even if that is not always the case. Recent images from Abu Ghraib and Fallujah offend the national sense of decency. While there are always those who will rush to defend each atrocity as a unavoidable response in the war against terrorism, there are many more whose feelings range from disappointment to disgust. The armed forces themselves are taking these incidents seriously and are trying to maintain some humane standards, but will that be enough to keep barbarism at bay?

Unfortunately, the insurgents in Iraq will do anything to drive the occupying forces out. They have killed civilians, faked surrenders in order to draw out U.S. troops, booby-trapped corpses, and beheaded hostages. And while the temptation is there to ignore the rules of civilized warfare and to adopt their tactics, doing so will only strengthen the insurgency and bring down more international outrage.

The United States is faced with a difficult choice. On the one hand, the leadership in Washington and Baghdad can forget the Geneva Conventions and allow — or even encourage – the soldiers in the field to be as brutal as possible. This will just make the enemy stronger and put the United States in violation of international law. Or the armed forces can continue to fight hamstrung by humanitarian rules, leaving the soldiers exposed to ever more dangers. Americans like to believe that the moral fabric of their nation will not allow them to become war criminals, even if that means losing a war. It is time to admit this and start preparing an exit strategy for Iraq.