Watching the rapid disintegration of security in Syria and the U.S. withdrawal, Marty Palmer recalled the night an Islamic State car bomb exploded near the Kurdish unit partnered with his Army Special Forces team.

The attack in the summer of 2017 killed about eight Kurdish fighters, Palmer said. U.S. soldiers spent much of the night patching up about a dozen survivors, who were then whisked away to a nearby Kurdish medical facility.

“I look at that event and it stands out to me as so representative of the sacrifice the Kurds made in the fight against ISIS,” Palmer said, using an acronym that describes the Islamic State. “It’s just one of many instances where they showed that type of bravery. The very next day, they were right back at it.”

Palmer, 32, is among several thousand U.S. troops and veterans who served in northern Syria and are witnessing the messy end of a years-long alliance with the Kurdish-led Syrian Democratic Forces.

The U.S.-backed militia has been one of America’s closest partners in the war against the Islamic State since 2014, and some 11,000 Kurdish fighters have been killed in combat against the terrorist group. But with President Trump’s order to withdraw all 1,000 U.S. troops from northern Syria in the face of a Turkish offensive, those who have served alongside Kurdish forces are left to consider America’s new place in the world.

“It feels like we’re abandoning our closest ally in the fight against ISIS, and we’re abandoning them to a fate that is going to end very poorly for them,” said Palmer, who left active duty last year. To “completely abandon” a force that has “given thousands of lives for this conflict is really tough to watch.”

U.S. veterans have supported Trump in part because of his often-repeated promises to extricate the U.S. military from a generation at war, numerous polls have found. But the calamity on the ground in Syria has wrought angry reactions from service members like few other recent foreign policy decisions.

Troops have reacted viscerally in interviews and on social media despite Defense Department restrictions on them expressing political opinions. Some who served in northern Syria also have spoken out despite associations with secretive Special Operations units that rarely speak to the media and do not want their service members identified.

The sequence of events have played a significant role in that.

On Oct. 6, the White House announced that the United States would not stand in the way of a Turkish military offensive to remove the SDF near Turkey’s border, despite two years of U.S. troops effectively serving in the area as a guard against just that.

The Pentagon pulled about 50 service members away from two Syrian border towns before the offensive began, and Trump ordered a quick withdrawal of the remaining 1,000 U.S. troops in northern Syria on Saturday after the violence spiraled out of control and SDF leaders who had relied on the United States sought help from the Syrian regime, which is backed by Russia and Iran.

Defense Secretary Mark T. Esper said Sunday that Turkey had indicated it would launch its offensive “regardless of what we did” and that there was “no way we could have stopped 15,000 Turks.”

But at least eight U.S. service members who served with Kurdish forces in Syria and Iraq expressed disgust in interviews with The Washington Post about the rapid U.S. changes and the lack of a clear plan to prevent a crisis. Many of them, speaking on the condition of anonymity because of the sensitivity of the issue, doubted that Turkish forces would have launched an assault into northern Syria if the White House had not said it would stand aside.

“I can’t even look at the atrocities,” an Army officer who served in Syria last year said of videos posted online of Turkish-backed fighters executing Kurdish civilians. “The ISIS mission is going to stop, ISIS is going to have a resurgence, and we’re going to have to go back in five years and do it all again.”

He added that while he was in the Middle East, military officials at the Pentagon sometimes discussed with officers in the field how they could craft a compelling case for Trump to stay longer while a thoughtful exit strategy could be designed.

“I remember hearing, ‘How are we going to phrase terms to convince Trump not to go off a cliff?’ ” the officer said. “It’s like, ‘How do you steer him to the right decision and not where he wants to go?’ ”

Another Army officer who deployed to Syria a few times and has knowledge of ongoing operations predicted in an interview Saturday that if the United States didn’t change its policy within 48 hours, “everything over the last five years is done.” Within hours, Trump had ordered a full U.S. troop withdrawal from northeastern Syria.

The officer said the United States aided the Turkish offensive by talking the SDF into taking down some of its defenses in the border region under the premise that the United States would stay involved and then allowing the Turkish operation to go forward.

“Folks are heartbroken,” the second officer said. “It’s very different than if we had said, ‘We are getting out of Syria in six months.’ Reasonable-man definition says that we facilitated that attack.”

The abrupt change followed more than a year of Trump pressing to get U.S. troops out of Syria, with directives for the military to withdraw passed in April and December 2018. The latter one prompted Defense Secretary Jim Mattis to resign, but in both cases, senior advisers talked Trump into slowing down.

One Special Forces soldier with several deployments to northern Syria said he blamed senior military leaders for not finding a way out of Syria faster given Trump’s well-known desires.

The Kurdish forces fought hard, but the U.S. partnership with them was always going to be problematic, he said. The Kurdish fighters in Syria have links to the Kurdistan Workers’ Party, or PKK, in Turkey, which both Ankara and Washington have labeled a terrorist organization.

“If someone had presented Trump with a six-month withdrawal plan and actually stuck to it, we wouldn’t be having these conversations,” the soldier said. “You can tell me horror stories and show me intel reports, and none of it would matter to me. I fully support withdrawing from Syria.”

Early in Special Forces training, soldiers are taught not to “fall in love with your partner force,” he said. That means they learn to build up other groups like the SDF, but only in support of U.S. interests. He recalled seeing Kurds in Syria hoist a banner of Abdullah Ocalan, the PKK’s jailed leader, after one operation and wearing PKK memorabilia on their uniforms.

“Our collective entity in Syria tried to explain to them: ‘You can’t do that. If you do that, it puts us in a very precarious position, and we are providing unparalleled and unequaled-in-history air support.’ ” he said. “They still did it.”

Other soldiers said Turkey’s anger about the United States teaming up with Kurdish forces had been managed for more than two years and could continue to be contained. With teams of U.S. service members right along the border in Syria, they said, it was unlikely that Turkey would want to get into a war with the United States after their decades-long alliance in NATO.

Army Secretary Ryan McCarthy, asked Monday about the service members’ criticism on Syria, said he likes candor but that soldiers must not be disobedient.

“Everybody has an opinion in a war of ideas,” he said, speaking at a conference of the Association of the U.S. Army. “But ultimately, when national policy decisions are made, we salute and move out.”