Much has been written of the monetary debt we've piled up for future generations. The scope of the problem is indeed mind-boggling because we're talking in trillions. It would take a stopwatch about 315 centuries to tick off a trillion seconds. That's 31,500 years. The span of recorded history is about 10,000 years, so the time line of human civilization on the planet comprises less than one-third of a trillion seconds. Yet we'll borrow some $1.4 trillion this year just to pay the nation's bills.

As daunting as these numbers are, we're also racking up a different kind of debt that could prove even more painful to repay. I refer here to the blood debt we incur when we kill in the national interest. Remarkably, most people seem oblivious to the implications of this hazard.

When news broke that Osama bin Laden had been killed in a daring commando raid, cheerful throngs gathered in the street to celebrate. While bin Laden's execution was both justified and overdue, details of the event provide chilling insight into operations of this nature.

Navy SEAL Team 6 struck at night, deploying against an objective whose defenses turned out to be surprisingly light. Intelligence had tracked bin Laden to this location by following one of his couriers. That man fired on the incursion team from an outer building in the complex and was quickly dispatched.

The commandos then entered the first floor of the main building where they killed the courier's wife, his brother and one of bin Laden's sons. The raiding party proceeded up to the third floor where they saw bin Laden stick his head out of a bedroom door. One of the SEALs fired at him, missed and bin Laden retreated back into the bedroom, slamming the door behind him.

The commandos subsequently forced the door and confronted the target and one of his wives. The wife attempted to intercede on her husband's behalf and was shot in the leg, after which bin Laden was mortally wounded with rounds to the head and chest.

The mission was understandably hailed as a major success. The president met personally with the SEAL team to commend its members for their accomplishment. If a squad of cops had conducted the same operation, however, they'd now all be charged with murder.

That's because the police are required to follow a continuum of force and are allowed to employ only the minimum force necessary to control the situation. That continuum begins with a verbal command and escalates through intervening stages to deadly force.

Generally, the police can exercise one level of force above that threatened by their adversary. A suspect who attempted to punch an officer, for instance, could be struck with a police baton, sprayed with chemical mace or shot with a Taser, but his action would not normally justify lethal force.

The military, on the other hand, is intended to do battle rather than make arrests. Troops begin with the assumption that they are confronting an armed enemy, thus turning the continuum of force on its head. The distinction is more than academic.

PBS recently aired a Frontline documentary detailing a kill/capture operation in Afghanistan. These raids, usually conducted at night, are intended to eliminate specific targets while minimizing collateral damage to the community at large.

In the featured incident, American soldiers enter the targeted premises accompanied by Afghan troops whom they're training. A tribal elder and his family are lined up against a wall at gun point while the house is ransacked. Legal niceties like search or arrest warrants are conspicuous by their absence.

The elder protests that he has no ties to the Taliban and explains that he is an important leader in the peaceful village. The Afghan authorities express sympathy but explain that they are powerless to interfere with the Americans. The humiliated elder is subsequently handcuffed in front of his family and carted off for interrogation. We learn later that he was ultimately released without being charged.

According to Frontline, the United states has conducted over 12,000 of these raids in the last two years as part of the "surge" in Afghanistan. Resistance is met with lethal force when warriors impersonate peace officers.

Imagine for a moment that the situation was reversed -- that Afghan troops were conducting these raids in your neighborhood. How many hearts and minds do you think they'd win? Would there be any hard feelings over the occasional case of mistaken identity or accidental killing?

We went to Afghanistan nearly 10 years ago to eradicate al-Qaida. According to CIA estimates, between "50 and 100" al-Qaida operatives are left in the country. As we have 140,000 troops deployed there, we have a minimum of 1,400 troops for every remaining terrorist. Meanwhile, we're creating new enemies out of the indigenous population every night.

It strikes me as unlikely in the extreme that we'll be able to kill and kidnap our way to a viable Afghan democracy. And as even the most benevolent occupying army eventually wears out its welcome, it would seem to be time to go home. Our blood debt is already steep enough.