Washington — At a gathering last Saturday night of military and intelligence veterans, one topic shrouded the room: President Trump’s decision to abandon Kurdish fighters in Syria who had fought and died to help America destroy the Islamic State.

“It’s a dagger to the heart to walk away from people who shed blood for us,” one former top CIA official who attended the black-tie dinner told me later. A retired four-star general who was there said the same thing: Trump’s retreat was an “unsound, morally indefensible act” and a “disgrace” to America and the soldiers who serve this country.

This sense of anguish was pervasive among those attending the event, several attendees said. It was an annual dinner honoring the Office of Strategic Services, the secret World War II commando group that was a forerunner of today’s CIA and Special Operations Forces. The event celebrated the military alliances that have always been at the center of American power. It was a bitter anniversary this year.

It’s probably impossible for Americans to fully grasp the sense of betrayal felt by the Syrian Kurds, who suffered 11,000 dead and 24,000 wounded in a war that we asked them to fight. But perhaps we can understand the shame and outrage of the Special Operations Forces who fought alongside them and now see the Kurds cast aside to face their Turkish enemies alone.

“It will go down in infamy,” said one Army officer who served in the Syria campaign. “This will go down as a stain on the American reputation for decades.” Those may sound like extreme sentiments, but they’re widely shared by those who served in the Syria mission. For these soldiers, abandoning an ally on the battlefield is about the worst thing that can happen.

To explain what the war looked like to the Americans who served in Syria, I’ve gone back through my notes from four trips there with the U.S. military. I never encountered a soldier who doubted that the war made sense.

On my first trip in May 2016, I spent several hours talking with a tall, thick-bearded American officer, both arms decorated with sleeves of tattoos; he looked like a video-game action hero. He scoffed at Turkish claims that the Syrian Democratic Forces (SDF), led by a Kurdish militia called the YPG, was a terrorist cult. “They stand their ground,” he said. That seemed the highest compliment he could give.

The war moved quickly, as the SDF went house to house, clearing jihadis, and America rained bombs from the sky. In July 2017, rumbling down a dirt road near Tabqa that, in theory, had recently been de-mined, a sergeant major from Oklahoma is playing country music super-loud on the radio. He talks about home, but it’s obvious, listening to him, that there’s nowhere he and most of his colleagues would rather be than right here.

We sit for a meal on the floor with the Kurdish commanders who have just seized Tabqa in a costly assault. They tell us it’s their duty, and they keep pushing more food at us. In the concrete tower where the Islamic State had hurled homosexual prisoners to their death, all that’s left are trash heaps and jihadist slogans painted on the walls.

By February 2018, the Islamic State capital of Raqqa is just a pile of rubble. As we drive through the caverns of shattered concrete, children start waving to the soldiers, the way civilians do after any war, probably because they’re so glad it’s over. I meet an American doctor who’s the only trauma surgeon in the area, who spends all day, every day, treating severely wounded Syrians. She says it’s an “honor” to be in Syria.

And now, as we near the end of the story, it’s July 2019, and I’m in Kobani meeting with Gen. Mazloum Abdi, the Syrian Kurdish commander. Trump has announced in December that he wants to withdraw all American troops. Mazloum is too polite and loyal to criticize the American president. “We respect any decision made by the U.S., whether they want to stay or leave,” he says in a calm, flat, battle-hardened voice.

American officers tell me later that Mazloum has been criticized for being too trusting in America, but Mazloum keeps insisting that he has confidence in his allies. I ask one of the U.S. officers what it was like to tell Mazloum in December that the U.S. would be leaving. The answer isn’t printable.

What do these American soldiers feel as they watch Trump retreat from the Syrian battlefield and leave their former comrades to die? They feel sick.

— David Ignatius is a columnist for Washington Post Writers Group.