Among those who served in Afghanistan—America’s longest war and, until recently, also America’s forgotten war—there was a joke, a bit of gallows humor, that made the rounds. It goes like this:

Knock, knock.
Who’s there?
Nine-eleven who?
Hey, I thought you said you’d “never forget.”

I’ve been thinking a lot about that joke lately. It’s been disorienting to see Afghanistan, a war so many cared so little about for so long, once again thrust into the headlines. But here we are, observing the 20th anniversary of 9/11 on the tail end of one of the most calamitous episodes in American military history.

The Biden administration will point to the 115,000 evacuees flown out before our final withdrawal from Kabul, but even the White House has conceded that we failed to evacuate even half the number of Afghans who’d worked alongside us and whose lives remain under threat by the Taliban, to say nothing of the hundreds of American citizens who remain trapped in Afghanistan, a number far larger than the 66 hostages inside the American Embassy in Tehran in 1979.

Defenders of the Biden administration have claimed this type of chaotic withdrawal was unavoidable. After all, they say, this was Afghanistan, the “graveyard of empires,” and so it was inevitable that our last days there would be chaotic, even if the Soviet withdrawal from Afghanistan, in 1989, across the Friendship Bridge, was a far more dignified affair. A focus on the withdrawal obscures a larger issue. What matters at the end of a war is the outcome. The outcome of Afghanistan’s end is American ignominy.

When we gather this week to mark 9/11, how will we honor that pledge to never forget? Obviously, we will remember the events themselves, the planes hitting the Twin Towers and the Pentagon, the heroic passengers of United Flight 93 who downed their plane in a Pennsylvania field.

Here we are, observing the 20th anniversary of 9/11 on the tail end of one of the most calamitous episodes in American military history.

We won’t forget the losses, either: the 2,958 victims of that horrific day. And we will remember our response—flawed as it was at times—that led to a generation of sacrifice made by men and women who volunteered to fight our forever wars. In the case of Iraq, we’ll remember a war waged on false pretenses and do our best to never forget that mistake.

However, there’s something else I hope we can remember and never forget: how America came together as a country in the days after 9/11, a type of unity that seems unimaginably elusive today.

Over the past few years, as our national discourse has devolved into stark partisanship, you may have found yourself in a conversation or two where you’ve wondered how our now hopelessly divided country would react to an event as cataclysmic as 9/11. Long before the pandemic, this was a question I often heard raised among friends of all political stripes, a parlor game where we’d wonder what national crisis would be required to bring us together again.

When the pandemic hit, it seemed like that crisis had arrived, and yet unity proved elusive. The opening years of this decade have been some of the most divisive in American history. While once we pledged to never forget the attacks of 2001, it seems that what we forget today, every day, is how not to attack one another.

America has a short memory; it’s in our DNA. People have always come here to re-invent themselves, to shed some portion of their old identity in order to claim a new one, as an American. You can’t do that without a little memory loss. But after the evacuation of Kabul, in which we saw Afghan refugees so desperate for freedom that they clutched the landing gear of an American C-17 aircraft as it took off, only to plunge to their deaths, it is worth asking whether this disastrous withdrawal has shown us that we’ve forgotten—or, worse, consciously betrayed—certain fundamental American values.

Since seeing those images of the C-17, I’ve been reminded of the speech given by Anthony Blinken as he accepted his nomination from President Biden as secretary of state. In it, he told the story of his stepfather, Samuel Pisar, a Polish Holocaust survivor. Blinken described how a very young Pisar was hiding in the woods after having escaped the Nazis when he heard the low, distant rumble of a tank. As the tank approached, Pisar recognized a five-pointed white star on its side. He knew only three words of English, taught to him by his mother, and when he flung himself on his knees and looked up at the tank’s commander, he said them: God bless America.

It’s a moving story. It evokes the refugee-and-immigrant element familiar to so many American families, including my own. In his closing remarks, Blinken reflected on why that American G.I. thought to snatch up his stepfather and whisk him to safety. “That’s who we are,” Blinken said.

Now look at what he’s presided over in Afghanistan. Look at what we have done. Look at the images of our Marines arriving home in flag-draped coffins. Or at the image of an Afghan baby being passed over the gate at Hamid Karzai International Airport because its parents weren’t allowed in. Look at the images of Taliban fighters flying American Black Hawk helicopters. Twenty years from now, I hope we will not have forgotten those images and what they represent. I hope the choices made over these last weeks are not “who we are.”

Elliot Ackerman is the author of, most recently, Red Dress in Black and White and a co-author of 2034. He is a former Marine and intelligence officer who served five tours of duty in Iraq and Afghanistan