AS A MARINE officer in Afghanistan and Iraq, I learned one of the Corps' cardinal rules: Marines don't leave their own behind.
This culture of selflessness is among the U.S. military's greatest assets - but leaves it especially vulnerable to the Iraqi insurgency's tactic of kidnapping and killing Westerners.
The beheadings of captured contractors and foreign aid workers have already been beamed around the world, but this horror would have truly strategic resonance if the target were an American soldier. The insurgents have not yet capitalized on this vulnerability, but they show every sign of learning quickly.
During the first week of the war in Iraq last year, a Marine sergeant was captured in the southern town of Ash Shatra. He was reportedly dragged through the streets and strung up to die in the central square. Part of my unit entered Ash Shatra to recover his body and avenge his brutal death.
We had battled daily in a netherworld of human shields, armed children, false surrenders and suicide bombers, learning to trust only one another. Despite all this, the sergeant's death rattled my Marines and me. The execution of one of our own fueled our most paranoid fears about the people whose hearts and minds we were supposed to be winning.
The next American serviceman or woman to be captured in Iraq will likely be exploited by an increasingly media-savvy insurgency. Consider the impact if viewers, over their morning coffee, were to confront the horror of a baby-faced 18-year-old Marine, or perhaps a petite female soldier, blindfolded and pleading for life.
Abu Musab Zarqawi's terrorist network specifically seeks to capture American military personnel, particularly one of at least 14,000 women serving in Iraq.
His organization's capacity for depravity surpasses anything we have yet seen, so the psychological value of such a prize is almost limitless.
Because U.S. policy rightly forbids negotiating with terrorists, we should expect to witness the televised butchering of an American soldier. The intent of this shock tactic would be twofold: to provoke an irrational response by our troops and to demoralize the American public.
Certainly we can all envision visceral and destructive reactions to publicized executions of Americans serving in Iraq. So what should the military - and Americans generally - do in response to this new type of warfare, fought less on the ground than in the psyche?
We can all learn something from the daily responses of our men and women in uniform. Soldiers and Marines in Iraq already know the costs of war. Each day, my platoon struggled to maintain its humanity in scenes too graphic for broadcast on the nightly news.
Despite the injustice and brutality, we knew that our enemies won whenever we responded indiscriminately. The best of our small-unit leaders know they must refuse to play into the hands of their provocateurs. Emotional responses to isolated acts of barbarity are no way to make policy.
And that's the lesson for the American people. The war in Iraq will be lost if hysteria or despondency gains the upper hand.
The insurgents cannot hurt us where we are strong, so they will hit us where we are weak. We must be ready for it.
On the third morning of the invasion, my battalion commander gave his officers advice that bears repeating: "Hope is not a method, nor is luck - hard work is."
We cannot merely hope the insurgency will fail to capture another American. Nor can we rely on luck to make it so.
Instead, all Americans must steel themselves for a new kind of work, girding our own hearts and minds against this latest horror.
Nathaniel Fick, a Baltimore native, served as a Marine Corps captain and is writing a book about his combat experiences.