As we observe this Veterans Day, the war on terror will have lasted more than ten years. For all that time, I have kept an outdated aeronautical chart in my flight suit. It’s a type of chart pilots use to orient themselves while flying in clear weather. My old chart provided guidance over New York City for what fliers call the river visual approach to La Guardia’s runway one-three.

The chart is a stick figure representation of Gotham from the air: its islands and rivers, its rectangle of Central Park, its highest points. The approach diagram depicts prominent landmarks, including the Empire State Building, the Statue of Liberty–and the World Trade Center. The Twin Towers appear to the right of the flight path, with a notation that says they rise to 1,742 feet.

This fading, tattered approach chart has flown with me on every military mission since 9/11. It’s there for when the days and nights get long–to remind me why we went to war in the first place.

When I examine the chart now, it triggers memories of an old airline job, of spotting the towers in summer haze and pointing them out to passengers. Even after ten years, I still cannot fathom the hatred that would lead someone to fly airplanes into buildings.

For a decade, those of us in the military have dealt with that hate head on. We have seen successes and failures, suffered heartbreaks and setbacks. On occasion, the U.S. has made mistakes that have harmed the innocent. But by and large, American forces have fought under the most careful and restrictive rules of engagement in the history of armed conflict. And no further major terrorist attacks have taken place on U.S. soil.

Glib comparisons to Vietnam began the day the first U.S. bomb fell in Afghanistan, and they continue now. The specter of Southeast Asia and the 58,000 Americans killed for little gain still haunt our body politic. But Afghanistan is a very different war, fought for very different reasons, by a vastly different military, on behalf of a different public.

In the years since Vietnam, our society has learned the hypocrisy of ordering troops to combat and then condemning them for going. Even after a decade of war, strangers see troops in uniform and thank us for our service.

We appreciate the thanks. But sometimes it seems tinged with pity, as if we’re victims of a calamity and not professionals who have shouldered a difficult but necessary burden.

That burden grows heavier with repeated deployments and shrinking resources. Yet it’s a burden that someone must carry.

Ten years ago, few people thought Operation Enduring Freedom would endure this long. I certainly didn’t. In some quarters, the very phrase “war on terror” has become unfashionable; talking heads in safe places note sagely that you can’t make war on a method, a technique.

Yeah, we know. But for sound rhetorical reasons, we don’t call it the war on Islamic extremism. That would make it too easy for extremists to twist the phrase into “war on Islam,” which it is not.

Rather, it is a war against a nihilistic cult that uses a twisted interpretation of Islam as a catalyst. Poverty does not explain a terrorist’s motivation. Most of the 9/11 hijackers came from middle-class backgrounds or better. Nor does injustice. What wrong does Taliban philosophy seek to right?

Consider home-grown American terrorists. Did Timothy McVeigh have a legitimate grievance? Should we have heeded Ted Kaczynkski’s Unabomber Manifesto? Foreign terrorists can claim no more justification than our own domestic fringe groups. They just have greater numbers, more funding, better organization. Until they tire of war, it doesn’t matter if we do.

However, war fatigue is understandable. A restaurant near my home, known for its support of progressive causes, has put a new sign in its window. The sign reads: “Imagine a World Without War.”

Historians, statement, and soldiers all the way back to Thucydides have tried to do that. The problem is there are other people imagining far different things.

My old aeronautical chart depicts a small section of a dangerous and imperfect world. I wish only success to those who would imagine it better. But those of us in the armed forces must deal with it as it is. I’d hate to imagine the world the terrorists would give us if they could.