"Amateurs talk strategy. Professionals talk logistics." That well-worn saying, sometimes attributed to Gen. Omar Bradley, contains an obvious element of wisdom. Modern militaries cannot fight without a lengthy supply chain, and the success or failure of major operations can turn on the work of anonymous logisticians.

Yet there is a danger of professional soldiers becoming so focused on supply lines that they lose sight of larger strategic imperatives. In Afghanistan and Iraq, we may already have crossed that threshold.

In the past few months, I have traveled across U.S. Central Command's area of operations a vast domain stretching from the deserts of Arabia to the mountains of the Hindu Kush. Everywhere, I have found massive bases fortified with endless rows of concrete barriers and stocked with every convenience known to 21st century Americans.

Some front-line units continue to operate out of spartan outposts where a hot meal is a luxury and flush toilets unknown. But growing numbers of troops live on giant installations complete with Wal-Mart-style post exchanges, movie theaters, swimming pools, gyms, fast-food eateries (Subway, Burger King, Cinnabon) and vast chow halls offering fresh-baked pies and multiple flavors of ice cream. Troops increasingly live in dorm-style quarters (called "chews," for "containerized housing units") complete with TVs, mini-refrigerators, air conditioning/heating units and other luxuries unimaginable to previous generations of GIs.

No one would begrudge a few conveniences to those who have volunteered to defend us. But the military's logistics feats come with a high price tag that goes far beyond the $7.7 billion we spend every month on operations in Afghanistan and Iraq. U.S. troops in those countries consume 882,000 liters of water and 2.4 million gallons of fuel every day, plus tons of other supplies that have to be transported across dangerous war zones. Centcom has more than 3,000 trucks delivering supplies and another 2,400 moving fuel each one a target that has to be protected.

Among the more surrealistic moments of my travels was pausing at a base near Baqubah a far-from-pacified Iraqi city that was Abu Musab Zarqawi's last base of operations to enjoy a fresh-brewed iced latte at a Green Beans coffee shop. It hit the spot, but when I later told a Marine captain about the experience, he took away some of my enjoyment by asking, "I wonder how many men had to die to get those coffee beans to Baqubah?"

Good question. Supply lines are indeed vulnerable. So are the bases themselves. Keeping everything running safely and smoothly eats up a lot of scarce manpower. According to Centcom, there are 20,000 combat service support troops in its area of operations and another 80,000 contracted civilians. (The U.S. has a total of 150,000 troops in Afghanistan and Iraq.) The latter figure no doubt includes many private security guards, but numerous soldiers are also needed to protect all of these logistics lines, and casualties are inevitable.

In large part for reasons of security and convenience a few big installations are easier to defend and supply than a lot of small ones more and more soldiers and support personnel are congregating in a handful of mega-bases, such as Logistics Support Area Anaconda in Iraq, which has about 30,000 inhabitants. When spending time on such installations, it's easy to forget where you are. The only reminder that you're not in Ft. Hood, Texas, comes in the form of occasional, inaccurate mortar rounds or rockets fired by insurgents.

Successful counterinsurgency operations require troops to go out among the people, gathering intelligence and building goodwill. But few Iraqis are allowed on these bases, and few Americans are allowed out and then only in forbidding armored convoys.

Most of our resources aren't going to fight terrorists but to maintain a smattering of mini-Americas in the Middle East. As one Special Forces officer pungently put it to me: "The only function that thousands of people are performing out here is to turn food into [excrement]."

How to explain this seemingly counterproductive behavior? My theory is that any organization prefers to focus on what it does well. In the case of the Pentagon, that's logistics. Our ability to move supplies is unparalleled in military history. Fighting guerrillas, on the other hand, has never been a mission that has found much favor with the armed forces. So logistics trumps strategy. Which may help explain why we're not having greater success in Iraq and Afghanistan.