When President Jose Biden announced on Wednesday that the United States would withdraw all its troops from Afghanistan by Sept. 11, 2021, he appeared to be finally bringing this "forever war" to an end. Although I have waited for this moment for a decade, it is impossible to feel relief. The Sept. 11 attacks took place during my senior year of college, and the wars in Iraq and Afghanistan that followed consumed the entirety of my adult life. Although history books may mark this as the end of the Afghanistan war, it will never be over for many of my generation who fought.

Sometimes there are moments, no more than the span of a breath, when the smell of it returns and once again I'm stepping off the helicopter ramp into the valley. Covered in the ashen dust of the rotor wash, I take in for the first time the blend of wood fires burning from inside lattice-shaped mud compounds, flooded fields of poppies and corn, the sweat of the unwashed and the wet naps that failed to mask it, chicken and sheep and the occasional cow, the burn pit where trash and plastic smoldered through the day, curries slick with oil eaten by hand on carpeted dirt floors, and fresh bodies buried shallow, like IEDs, in the bitter earth.

It's sweet and earthy, familiar to the farm boys in the platoon who knew that blend of animal and human musk but alien to those of us used only to the city or the lush Southern woods we patrolled during training. Later, at the big bases far from the action, surrounded by gyms and chow halls and the expeditionary office park where the flag and field grade officers did their work, it was replaced by a cologne of machinery and order. Of common parts installed by low-bid contractors and the ocher windblown sand of the vast deserts where those behemoth bases were always located. Relatively safe after the long months at the frontier but dull and lifeless.

Then it's replaced by the sweet, artificial scents of home after the long plane ride back. Suddenly I'm on a cold American street littered with leaves. A couple passes by holding hands, a bottle of wine in a tote bag, dressed for a party, unaware of the veneer that preserves their carelessness.

I remain distant from them, trapped between past and present, in the same space you sometimes see in the eyes of the old-timers marching in Veterans Day parades with their folded caps covered in retired unit patches, wearing surplus uniforms they can't seem to take off. It's the space between their staring eyes and the cheering crowd where those of us who return from war abide.

My war ended in 2011, when I came home from Afghanistan eager to resume my life. I was in peak physical shape, had a college degree, had a half-year of saved paychecks and would receive an honorable discharge from the Marine Corps in a few months. I was free to do whatever I wanted, but I couldn't bring myself to do anything.

Initially I attributed it to jet lag, then to a need for well-deserved rest, but eventually there was no excuse. I returned to my friends and family, hoping I would feel differently. I did not.

"Relax. You earned it," they said. "There's plenty of time to figure out what's next." But figuring out the future felt like abandoning the past. It had been just a month since my last combat patrol, but I know now that years don't make a difference.

At first, everyone wanted to ask about the war. They knew they were supposed to but approached the topic tentatively, the way you hold out a hand to an injured animal. And as I went into detail, their expressions changed, first to curiosity, then sympathy and finally to horror.

I knew their repulsion was only self-preservation. After all, the war cost nothing to the civilians who stayed home. They just wanted to live the free and peaceful lives they'd grown accustomed to — and wasn't their peace of mind what we fought for in the first place?

After my discharge, I moved to an apartment near the Brooklyn Heights Promenade, overlooking downtown Manhattan. I'd sit and stare across the river to the gap in the skyline where I tried to imagine those two towers I'd never seen in person as people passed by laughing and posing for pictures. Part of me envied their innocence; another part was ashamed of them, and of me for wanting to be like them, and of the distance between us.

But necessity forced me to move on and ignore those thoughts. I found a job, I dated, I made new friends, and I spent time with family. I pretended to be the man everyone expected me to be again after the war. But the memories remained.

I reached those milestones others measured their life by, but they meant nothing to me. As the thoughts became more demanding, I dismissed them with distractions. I worked longer hours, broke up with partners, sought different friends to replace the old. But like that nightmare in which the harder you run, the slower you move, the thoughts were impossible to evade.

Now with the hangover after a night of drinking alone comes the stabbing thought: Did I survive the war for this? The once simple pleasure of an idle Sunday is undeserved because it has been paid for by the fallen and is no longer mine alone to spend. My dreams have been replaced by memories.

The past isn't a psychological problem that can be medicated, changed or forgotten; it's all I am. Those times when I do forget, it's the forgetting itself that feels wrong. The actions and decisions I made at war are the most important thing I have. After all, I wasn't a victim but a collaborator.

It's not guilt, shame or regret but that feeling of having done a terrible duty. And when it ended, the only thing left was to shoulder the burden and keep walking in the long line of march as we'd trained to do so many times before. A person can bear any burden for a good enough reason, but the more the weight digs into my shoulders, the less I recall why I joined in the first place.

I'd written a letter on the eve of my deployment, in case I was killed, and it's the last evidence I have of who I was before the war and why I fought. The first paragraph reads, "It was worth it," then it continues about honor, duty and patriotism before closing with a final farewell and a request for burial at Arlington.

"It was worth it." The words reverberate. The weight feels a little heavier, and I whisper them like a mantra and continue marching. But now the war is ending, and those words are enigmatic.

Was it worth it? Everything has been because I'd been able to answer yes to that question. But what if the answer is no?

For a long time, my faith that the war might be won quieted moments of doubt. I'd been back for only a few weeks when one evening I received message after message telling me to turn on the television. President Barack Obama announced that we'd finally killed Osama bin Laden, and the news cut to crowds outside the White House and ground zero, cheering. After almost a decade of war, it could end.

I remember I once asked a village elder whether he knew why I was there. He responded that we'd always been there. Confused, I asked him about the attacks on America. He said, "But you are Russians, no?" After 30 years of war, it didn't matter to him who was fighting but only that there was still fighting.

And what of the Afghan people, who will remain at war long after we leave? What of the kids who followed us on patrol and attended the schools we built? Did they grow up to be Taliban, just as our children grew old enough to fight in this war?

My first night in Afghanistan, a platoon sergeant told me he stayed awake each night thinking about what the children playing barefoot in the dirty, bomb-strewn roads dreamed about at night. After seven months, he had no answer. When my deployment ended, I too was no closer to an answer.

But now I know: They dream of war.

As time goes by, the most meaningful part of my life — and only its prologue — is being erased by time, by the enemy and even by my country. Although Afghanistan will dominate a few headlines now that it is ending, it no longer leads the evening news, and when it does appear in print, it's buried deep in the back pages along with the rest of the violence that happens only to people in other countries. Unable or unwilling to solve the problem, the average American is once again content to forget it exists, just as we were on Sept. 10, 2001.

But to me it feels wrong to forget or to move on. Maybe that's because the only recourse I have left is to remember. I am terrified of the day when I will have the final memory of what happened over there — not because it will be my last but because it will pass unnoticed. The dead, like the war, will finally be forgotten, and there will be nothing to mark their grave.

Timothy Kudo, a former Marine captain who served in Iraq and Afghanistan, is working on a novel about the Afghanistan war. He wrote this article for the New York Times.