The occasion for my visit was Valiant Shield, a military exercise--and the largest display of U.S. military power in the Pacific since the Vietnam War--in which several B-2s would be participating. Valiant Shield 2006 featured three aircraft-carrier strike groups, with all of their attendant destroyers, cruisers, frigates, submarines, and aircraft--290 aircraft in all, including B-2s, Marine F-18Cs, Navy F/A-18Es, and Air Force F-15Es. Never mind the official rhetoric--the point of this show of force was to impress adversaries like North Korea and competitors like China. (China had been invited to send a military delegation; the day before I arrived, Chinese officials were inspecting the bombers from the outside.)

Andersen Air Force Base has long had a squadron of heavy bombers, deployed there to be close to Taiwan and the Korean Peninsula. On one of my previous visits to the base, in the autumn of 2004, I'd spent time with B-52 pilots from Barksdale Air Force Base, near Shreveport, Louisiana. They were young, happy-go-lucky, uncomplicated. I was profoundly curious about the B-2 pilots. For a host of reasons, they had to be different.

A B-2 Spirit costs roughly as much as a fast-attack nuclear submarine or a guided-missile destroyer. But whereas a Los Angeles-class submarine requires a crew of 130 and an Arleigh Burke-class destroyer a crew of 320, the B-2 has a crew of just two: a pilot and a mission commander. There are only 21 B-2s in the Air Force. Nobody else in the U.S. military is entrusted with as much responsibility, in terms of sheer dollars, as these bomber pilots are. If a single B-2 were to go down, even in training, it would be a banner-headline story.

So who are these guys?

The pilots I was embedded with were from the 393rd Bomb Squadron, out of Whiteman Air Force Base, near Kansas City, and they were in Guam on a four-month rotation. The 393rd is the squadron whose planes dropped the atomic bombs on Hiroshima and Nagasaki. In fact, the current commander is the grandson of Colonel Paul W. Tibbets Jr., the pilot who flew the Hiroshima mission in 1945. Lieutenant Colonel Paul W. "Nuke" Tibbets IV grew up in Montgomery, Alabama, and graduated from the Air Force Academy. He was one of several B-2 pilots whose quarters I shared.

Another of the B-2 pilots I roomed with, also an academy graduate, was Captain Jim "Genghis" Price, from Mesquite, Nevada. Tibbets had gotten his call sign because of his grandfather; Price earned his by destroying a line of suspect buildings in Afghanistan with a "stick" of 28 500-pound bombs, and then dropping cluster bombs on nearby cave entrances. This was in early 2002, during Operation Anaconda, and he was flying a B-52 Stratofortress--or BUFF ("Big Ugly Fat Fucker"), as pilots call that hall-of-fame bomber, which made its debut in Vietnam.

Nuke Tibbets and Genghis Price were both inspired to join the Air Force by their Army dads. That's right: Tibbets's unfamous father, not his famous grandfather, had the most influence on his career.

"My grandfather was the ultimate warrior," Tibbets told me in a mild southern accent that's been fading during his years away from Alabama. "He was a gruff man of few words, whose real historic accomplishment was the B-29 unit he had organized and trained, which ended World War II. The fact that he personally flew the plane that dropped the first atomic bomb reflected his belief that the ultimate warrior is always in the front line. But it was a detail compared to his organizational accomplishment.

"For my grandfather, the mission was everything, which meant his family suffered. He divorced my grandmother and so wasn't around a lot when my dad was growing up. My dad had terrible eyesight and so couldn't be a pilot. He became a pharmacist in civilian life and rose to become a colonel in the Army Reserve, commanding a deployable MASH-like hospital unit. But my father gently encouraged me toward the Air Force. Good on him that he never forced it on me.

"Once I was in the Air Force, my grandfather rolled into my life and influenced me to be a bomber pilot. In his day, my grandfather wanted to fly bombers, as they were taking the fight to the enemy, while pursuit aircraft were supporting that effort."

For Price, the path was simpler. His father was an Army sergeant at Fort Carson, Colorado--close to the Air Force Academy--and all Genghis ever wanted to do was fly jets in combat. "It's a sappy story, but it's true," he told me in a permanently eager, cheerful voice. "In high school, I played sports, joined all the clubs, ticked off all the activities that would just help me get into the academy."

Genghis is a practicing Mormon who has served on religious missions to Latin America. Macho isn't a word one would associate with him, or with Nuke. Instead, they exude a humble, introspective star quality. When I asked Nuke what attributes he and others look for when selecting members of the squadron, he said, "People who are team players to such an extent that they are self-starters, and who never want to be noticed or recognized."

Nuke and Genghis are both of average height, with taut bodies--Price weighs only 126 pounds--and tense expressions. Their physiques match their quiet, precise personalities. The BUFF pilots I'd met were boisterous, hard-charging types; the B-2 pilots were older and calmer, with patience forged by-to use one example--29-hour hauls from Whiteman to Kosovo. These were continuous flights, with two aerial refuelings before the planes even entered the war zone. Nuke and Genghis didn't have nine Gs available to them to avoid enemy fire. They depended on getting into and out of a battle space unseen.

No plane is invisible to radar. The trick is to reduce an aircraft's "signature" so that you can "get iron past" a screen of overlapping surface-to-air missile sites. A B-2 is able to penetrate such screens because its boomerang shape gives it a severely reduced signature. It can drop as much ordnance as an entire squadron of fighter jets, directing bombs to their targets with GPS tail kits. All of this requires meticulous planning--the crux of a B-2's mission.

I saw no nude pinups on the B-2 pilots' walls or computer screens; rather, I saw photos of wives and kids, and I heard many references to community service and church. The pilots rarely cussed, unlike almost everyone else I've met in front-line military units. And they were less transient: A B-2 pilot can spend five years stationed at Whiteman, whereas other combat Air Force pilots bounce around the country and the world; until recently, regular Air Force pilots changed locations every two years. The B-2 pilots' lifestyle helps keep families together.

Although the Air Force is run by aggressive fighter jocks, the B-2 men are, in a deeper sense, the ultimate Air Force pilots. A comparison with naval aviators helps illuminate their mind-set. Navy pilots have a reputation for being screaming-off-the-carrier-deck daredevils; alone in the ocean, without issues like noise restrictions to worry about, they have fewer rules. Naval aviation is about what you can do with an aircraft; Air Force aviation is about what you can't do. Begotten by the U.S. military in 1947, the Air Force had its character molded by the Cold War's Strategic Air Command, the core of our nuclear-delivery system. Because of their awesome strategic responsibilities, Air Force pilots are more by-the-book, more operationally conservative, than their Navy counterparts.

And B-2 pilots, in particular, have deeply internalized remnants of the Cold War sensibility. Being with them gave me a palpable sense of the terrifyingly complex struggles that may lie ahead. The squadron's group commander of operations, Colonel Robert "Wheels" Wheeler, summed it up this way: "How do you take out a chemical-biological site of a rogue nation with surety, without inadvertently killing thousands of innocent civilians downwind? Well, the best way to avoid collateral damage would be to obliterate the site in place, with a weapon that either buries the site or burns it completely."

If we have learned anything since the Berlin Wall fell, it is that nothing can be ruled out. When the B-2 was developed, in the 1980s, part of the thinking was that the pressure to counteract such a stealthy and powerful nuclear bomber would lure the Soviets into further wrecking their economy. Few expected that the plane would be anything more than a theoretical asset, especially after the Cold War ended. Then came the war in Kosovo.

The 1999 conflict represented a breakthrough for the Air Force: Rather than a multiplane carpet-bombing strategy, we deployed just a few B-2s, each one hitting multiple targets with the superaccuracy of a fighter jet. Suddenly, aerial warfare was no longer about how many planes were needed to take out a big target, but about how many targets could be taken out with a single plane. The conflict in Kosovo also demonstrated that technology could permit the waging of limited wars. The B-2 allowed President Bill Clinton, who had little appetite for incurring casualties in a humanitarian intervention, to launch strikes with minimal risk to the pilots.

  The B-2 has subsequently been used in Afghanistan and Iraq, where, as Colonel Wheeler noted, "The B-2 makes a statement. And that statement is, 'We mean business!'" He banged his fist on the table. Wheeler is the classic intense Air Force intellectual. He has degrees in both engineering and strategic studies and is a veteran of three wars and a diplomatic posting in Europe. His insights came in hyperactive bursts between sips from a quart-sized plastic coffee mug.

"The deterrence effect of this airplane may be as important as its destructive capability," he went on. "Any adversary knows that the B-2 can enter relatively unseen with the power and accuracy to destroy. Merely by having the B-2, we can better influence the decision-making process in rogue nations and encourage any other countries to perhaps go another route in their national defense. The stealth bomber is a diplomatic instrument as much as it is a military instrument." Wheeler didn't say this explicitly, but for rogue nations, you should read "Iran and North Korea"; for other countries read "China and a resurgent, nationalistic Russia."

As countries like Iran and North Korea put more and more of their critical facilities deep underground, in places that cruise missiles launched from such offshore platforms as submarines lack the kinetic energy to penetrate, the B-2's ability to drop heavier bombs becomes ever more important. If the United States ever attacks Iran, expect to be reading a lot about the B-2. And if we never do, the B-2 will have been a hidden hand behind the muscular diplomacy that made an attack unnecessary.

Among soldiers and marines, there exists a brotherhood of warriors. But with sailors and airmen, the relationship is triangulated by technology--by an emotional bond to this class of ship or to that type of aircraft. The phenomenon is especially pronounced with the B-2.

  Take Michael "Bo" Baumeister, of Thousand Oaks, California, who retired as a chief master sergeant after 26 years in the Air Force and now works at Whiteman as a civilian for the Department of Defense, or "DOD," as he habitually calls it. Bo, a maintenance specialist for the B-2, is your typical good old boy, with a ball cap and country accent; he chews Skoal and hunts deer and pigs. "Why did you go to work for the government, rather than for a private contractor, where you could make real money?" I asked him. "I couldn't see leaving her," Bo replied, referring to the B-2. "And DOD offered me the chance to stay with the plane."

He explained further: "It's a pride thing. We're the B-2. We not only kick down your door, we go in and out of your country without you even knowing it. We take out your head of state, your nuke and chem-bio plants, your SAM [surface-to-air missile] sites. 'Follow us. We clear the path,' we say to the other aerial platforms."

I understood Bo's poignant, if over-the-top, infatuation with the plane. Indeed, a B-2 is endlessly fascinating merely to look at. The official Air Force description has it right: The B-2 is not so much a plane as a "flying wing," ajagged gray-black wedge with a small bubble rising out of its center, which is where the pilot and mission commander sit. Seen head-on, the bubble, with its dark windshield, looks like nothing so much as Darth Vader's mask. The ever-so-slightly-turned-down-beak design of the plane's front tip heightens the sinister effect. As you walk around the nose, the swept-back angle of the wings makes them disappear, and the plane seems to shrink in size, bringing to mind a small bat. But once you reach the back of the plane, the size of the wings becomes apparent, and you realize just how big the plane is. Its wingspan is 172 feet--greater than the distance covered by Orville Wright during his first flight at Kitty Hawk.

Look for another moment, and something else becomes obvious: All the things that normally protrude vertically from an airplane's wings--the fuselage, the engines, the tail, all the screws, rivets, tubes, and antennae--are part of the wings themselves. The four engines are snugly implanted on top of the wings, so that the plane becomes loud only when it's past you; it is quiet when it's approaching. The doors for the undercarriage and the bomb bays have razor-sharp edges that are sucked shut by hydraulic pressure, rendering the plane's exterior seamlessly smooth--no bends or ridges, however tiny; no angles that radar can bounce off. An electric current runs from one end of the plane to the other. This forces radar that hits the plane to skim across the wings rather than bounce off and send a signal. A whole section of the plane's maintenance crew is dedicated to the plane's "skin care."

One clear, sunny day in Guam, I became Spirit No. 374--the 374th person to fly in a B-2 Spirit since Northrop Grumman rolled it out of the hangar, in 1989. More people have been in space. Most of the B-2s are named after states. The plane I flew in was the Spirit of Georgia. The pilot was Major Justin "Mulligan" Amann, a graduate of Purdue University's Air Force ROTC program. The mission commander stayed on the ground to make room for me. Inside the cockpit was the mean smell of metal. With the door closed, there was just enough room for a fold-out cot, on which the crew could take turns resting during long flights.

I attached the buckles of my life-support harness to the ejection seat and connected the oxygen and communications gear to my helmet and face mask. Amann was already busy with the two laptops he'd brought on board to supplement the plane's computer system, which dates from the 1980s.

The B-2 is less about flying than about weapons programming and coordinating with other air and sea platforms. Adjustments to the rudders, elevons, and tail flap are made continuously by computers; the pilot doesn't have to worry about these tasks. However, coordinating with naval platforms can pose a challenge, because the Navy and the Air Force use different technological systems; as one pilot told me, harmonizing them is like merging Apple and Microsoft.

The maintenance crew had nicknamed our plane "The Dark Angel." Our call sign was "Death 62." The B-2 that would be flying alongside us was "Death 72." Violence is something no one in the combat Air Force apologizes for. The elite units of the military are about going to war, or "being able to play," as the troops put it. Senior Master Sergeant Kelly Costa, one of the maintenance men, told me that the most exhilarating moments of his professional life occurred when he was helping to load bombs onto B-2s before the "heavies" left for Kosovo and later Afghanistan.

  The flight itself, as I had expected, was not a thrill--nothing like a ride in a fighter jet. We rose and turned at degrees no more dramatic than those of a commercial airliner. After we reached 10,000 feet, Amann put the plane on autopilot. It continued to climb. We took off our oxygen masks, and he immediately got busy programming two missiles and 64 separate 500-pound munitions, which we dropped over Saipan--virtually, of course. I saw exactly what I would have seen had those bombs actually been released: hexagons, each representing an individual bomb, disappearing in twos from the computer screen. Had any of the bombs been nuclear warheads, the screen display wollld have been the same, but the weapons would have been a different shape.

The sky was near perfect. From 32,000 feet, the bands of cumulus clouds below us looked like occasional imperfections in the glazed surface of the Philippine Sea. Sunlight penetrated the water such that Saipan and Tinian appeared to be back-lit. Several times we flew over the old B-29 runways on Tinian, from which Colonel Paul Tibbets Jr. had flown the Enola Gay to bomb Hiroshima. At one point we unlocked the autopilot, and I flew the plane for 10 minutes. It was similar to sailing on instruments--a matter of making adjustments so that a vertical line stayed on, or close to, a dot on the screen. It struck me that the art of flying was being lost.

  Behind this ease of flight lay an entire world: the maintainers'. Deploying the four B-2s from Whiteman to Andersen had taken a maintenance crew of 155, as well as 130 pieces of rolling stockjammers, light carts, generators. Then there were the huge pallets of equipment, including the containers holding the 170 different chemicals used by the B-2, each of which requires customized climate-controlled conditions and must be disposed of according to strict regulations. The maintainers worked 12-hour shifts, in several buildings and hangars. To get the maintenance crew and equipment to Guam had taken one C-17 Globemaster and four C-5 Galaxies, transport planes so monstrous they dwarf the old standby C-130 Hercules.

Contemplating all of this led me to an unsettling realization: In most cases, it makes little sense to put assets that require so much ground support on forward bases. Because Guam is a U.S. territory, we can make a huge investment there without having to worry that we'll be thrown out. But there's no point in basing B-2s at sites controlled by other countries if in the midst of a crisis they might deny us permission to use them. Along with our other top-of-the-line aircraft, the B-2s should remain based primarily in the continental United States--which makes increasing the capacity for worldwide air-to-air refueling a key task for the Air Force.

Colonel Wheeler made the point that in future conflicts conventional assets like the B-2 and fast-attack submarines would be used in tandem with Predator drones, Special Forces A-teams, and Marine Corps platoons. Forget the debate about having needed more troops in Iraq after the initial invasion. As true as that might be, our military's primary focus in the next few decades will not be on massive troop levels; it will be on hitting specific targets with commando-style ground units that could call in air and sea strikes from platforms that are either untouchable or unseen. For example, during a war with a regional power like Iran, down-and-dirty planes like the A-10 and the AC-130, which typically provide close air support, would be less likely to be used than a high-altitude heavy like the B-2, after Special Operations teams have gone in on the ground for limited periods to identify targets for the planes' bunker-buster and other high-impact bombs.

Such operations would require an exponential increase in complexity--a greater variety of assets used in quick, symphonic offensives. "We may not be able to mass troops like we used to," Wheeler observed. "It's not just a matter of negative publicity from a global media, but of a profusion of competitors that will increasingly have the ability to hit such large formations with weapons of mass destruction. And that will be a chance we won't want to take.

"Think of bees swarming together in a hive, and then flying off again," he continued. "That's the military formation of the 21st century--lots of small joint air-land-sea configurations that combine instantaneously for a big attack and then separate out just as fast."

That's why many of the debates taking place today--about conventional versus nuclear weapons, about spending money on this aircraft versus that one--are simply beside the point. The issue is no longer what an A-team, or a submarine, or a Predator, or a B-2 bomber can do on its own; it's how these assets can be used in combination to leverage one another.

But that raises a larger issue: If the B-2 is necessary, for both our force structure and our negotiating credibility, as Colonel Wheeler believes it is, then its cost of more than $1 billion per plane is a truly depressing indicator of the price of empire. "Look at the rate of return al-Qaeda got on 9/11," one former civilian defense official told me. "For an investment of just a few hundred thousand dollars, they forced us to spend billions." In other words, as necessary as the B-2 might be, what's its rate of return--20 percent, perhaps? "I'm not saying that we require a rate of return like al-Qaeda gets," this former official went on, "but we'll need to narrow the difference if we're going to remain a great power."