The differing reactions to the alleged killing of noncombatants by American soldiers in the Iraqi town of Haditha reveal a troubling ignorance about the moral reality of war. Much of the national dialogue about the incident is being dominated by people whose approaches to making moral judgments on wartime actions are fundamentally flawed.

In one corner are those who are so convinced this war is wrong that they see only the bad things soldiers do in it. Such people are blind to all the good our soldiers and the war are accomplishing, and they revel in exploiting any incident of misbehavior by soldiers to smear all members of the armed forces and the entire war effort. By their logic, abuse of detainees by one platoon in one prison in 2003, or the alleged killing of civilians by one squad in one town in 2005, is conclusive evidence that the entire war effort is evil. These people are unable to reconcile the fact that unjust actions can and do occur within a war that nonetheless is morally justified.

In the other corner are those so convinced of the rightness of our cause that they refuse to acknowledge that our soldiers sometimes make choices that are clearly wrong and for which they should be held accountable. These people equate supporting the laws of war with being unpatriotic and disdainful of the troops. What they fail to recognize is that their implicit argument is both insulting to soldiers and corrosive to the foundation of the military profession. My fellow soldiers and I recognize fully that we are responsible for our individual actions, and that our permission to do violence to other human beings is constrained by our obligation to do so only when it is morally justified.

These polar positions are not novel. They are consistent with schools of thought that military ethicists refer to as the war-pacifist and war-realist positions, both of which fall outside the mainstream of the just-war tradition. What is disturbing is the way these competing perspectives have been hijacked by groups with political agendas and thus given a wider hearing than they deserve.

We should all reject such simplistic approaches to judging soldiers' actions in war. A combat zone is not some parallel universe where the nature of human beings or moral judgment is different. Combat is a human endeavor, and like any human activity it can be carried out morally or immorally, and moral judgments can be made on it.

In simplest terms, when soldiers are careful to target only enemy combatants and to limit unnecessary destruction and suffering, they fight morally. If they intentionally or negligently fail to abide by these restrictions, they fight immorally.

A harsh reality of war is that it involves large numbers of people making life-or-death decisions in very stressful conditions. Inevitably, as in all areas of life, some don't always conduct themselves as they should. Those who commit crimes should be held accountable, keeping in mind the extenuating circumstances of combat.

The circumstances of this war's battlefields are terribly complex. Soldiers find themselves conducting a wide range of operations, from war-fighting to policing, often during a single patrol, and those different operations require different principles for the use of force. It is often difficult for soldiers to discern which approach is appropriate and when. Not infrequently, a well-intentioned soldier ends up killing a noncombatant because of mistaken identity or some other factor caused by the fog of war. In such circumstances, we can say that the action is neither justified nor unjustified but that it is excusable. Not every wrongful death in combat is a war crime.

The good news is that well-trained, well-led soldiers can and do overcome the moral challenges of war and conduct themselves with great honor, and the great majority of American soldiers are well trained and well led. Although we fight an enemy who intentionally violates all norms of human decency and goads us to follow him into the abyss of wanton killing, America's soldiers continue to exhibit remarkable restraint.

What explains the difference between units that commit war crimes and units that don't? Leadership. This is the critical factor in ensuring moral conduct in war. When junior officers and senior noncoms train their soldiers to do what is right and when they maintain their composure and lead by example, their soldiers are able to retain their moral bearings despite the temptations and frustrations of battle. American military history reminds us that war crimes can be prevented by small-unit leaders with moral courage and judgment.

The Haditha incident is not likely to be the last time that we as a nation find ourselves judging the actions of our soldiers at war. All Americans should resist the calls of those who seek to condemn all soldiers based on the actions of a few, just as we should reject any claims that soldiers are immune from judgment. Instead, we should judge each soldier and situation on the merits, paying special attention to the circumstances in which thefateful decisions were made and to the actions of the soldier's leaders.

Peter Kilner is a major in the U.S. Army; the views expressed here are his own. He wrote this commentary for The Washington Post.