U.S. forces thought they killed a terrorist in Syria. They got the wrong man.

A U.S. drone strike in Syria last year killed a 56-year-old shepherd after confusing him for a terrorist leader, an internal investigation concluded, underscoring the Pentagon’s persistent struggle to avoid unintentional casualties despite the Biden administration’s pledge to curb such incidents.

The new assessment by U.S. Central Command, which oversees American military activity throughout the Middle East, affirms a Washington Post investigation published a year ago that cast doubt on officials’ initial public claim to have slain a senior al-Qaeda figure. A summary of the investigation’s findings was provided to The Post ahead of an anticipated release later Thursday.

Lotfi Hassan Misto was tending to his animals on May 3, 2023, in Qorqanya, a rural town in northwest Syria. Above, his movements were being tracked by an armed Predator drone. When U.S. forces fired a Hellfire missile into the rocky outcrop behind his home, commanders had confidence they were attacking a terrorist, officials said afterward. Instead, a defense official said, the suspected militant who had been their target slipped away and remains at large.

“The investigation determined U.S. forces misidentified the intended Al Qaeda target and that a civilian ... was struck and killed instead,” officials wrote in the investigation’s summary, which identifies Misto by name. He was the sole fatality, along with several of his sheep, according to video captured by first responders at the scene.

Thursday’s announcement offers little additional insight into how U.S. commanders and analysts botched the strike, saying only that it was “conducted in compliance with the law of armed conflict as well as Department of Defense and CENTCOM policies.”

The military’s investigation was opened about a month after The Post published its investigation on May 18 of last year.

In 2022, after years of scrutiny, the Pentagon said it would work toward reducing such incidents and increasing transparency when they do occur. The changes, enacted early in the Biden administration, were prompted by numerous investigations by the news media and other independent watchdogs that revealed how flawed intelligence and a dearth of clear-eyed analysis contributed to civilian deaths later minimized or excused away within the Defense Department and White House.

The defense official, who spoke with reporters on the condition of anonymity under ground rules set by the military, said the investigation showed that the botched drone strike was the result of “confirmation bias and insufficient red teaming,” a term the Defense Department uses for personnel tasked with stress-testing the decision-making during such operations to ensure their accuracy.

“The investigation revealed several issues that could be improved,” the command added, without providing specifics. “We are committed to learning from this incident and improving our targeting processes to mitigate potential civilian harm.”

The investigation was prepared by a one-star general who was assisted by 10 senior service members and civilians with relevant expertise but who were not involved in the deadly mishap, Central Command said. The work included interviews with more than 40 witnesses, and it sought information from nongovernmental organizations. It is unclear if any of the witnesses interviewed were civilians.

The investigation was completed in November. Officials did not explain why its findings were withheld until now.

The dearth of information disclosed by the military makes it difficult to assess if U.S. personnel acted recklessly in this case, said Oona Hathaway, an international law professor at Yale Law School. Yet the contours of the strike are similar to past incidents, she said, pointing to misidentification as a common factor in attacks that end in civilian bloodshed.

“The U.S. government doesn’t do enough to learn from its mistakes,” she said, citing her research on other U.S. airstrikes. “The exact same mistakes happen over and over and over again.”

Several issues remain unclear, including: who the intended target was, how he was able to evade U.S. forces, whether this failure allowed him to resume his suspected terrorist activities and, vitally, how U.S. personnel watching Misto never realized that he was the wrong man.

It is also unclear whether anyone will be held accountable for the deadly mistake.

“We had been tracking Misto for some time under the belief that he was the target,” the defense official said, declining to describe how long the surveillance occurred. Neighbors told The Post last year that such aircraft had circulated for about two weeks.

Priyanka Motaparthy, director of the Project on Armed Conflict, Counterterrorism and Human Rights at Columbia Law School, said the military appears to have conducted a far more robust investigation than others in recent years, but the response, she said, is inadequate.

“In every case we hear there was an unfortunate mistake,” she said, noting that the confusion between Misto and the target was particularly troubling. “There’s a legal requirement to have in place procedural safeguards to prevent acting on faulty intelligence and targeting the wrong person. … The fundamental right to life is at stake.”

Misto spent his life in Idlib province, where he married and started a large family of 12 children - eight daughters and four sons, whom he supported with work as a brick maker. He tended to sheep and chickens, staying close to home except when visiting his mosque. A terrorist life was preposterous, his family told The Post, for a man whose priority outside work and prayer was sipping tea with loved ones steps away from where he was killed.

Central Command’s statement is commendable in its admission of responsibility and pledge to learn from the strike, said Joanna Naples-Mitchell, an attorney previously in touch with Misto’s family and the redress program director at the Zomia Center, a humanitarian rights nonprofit. But the Pentagon’s immediate and sustained assertions of Misto’s links to terrorism were harmful, she said.

“In the future, the Department of Defense should take care not to make prejudicial statements regarding civilian status once an investigation has been opened,” she said in a statement. “In this case, such statements did further harm to a family that was already grieving the loss of a father, brother, and breadwinner. This, too, should be a lesson learned.”

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Omar Nezhat in Idlib, Sarah Dadouch in Beirut and Imogen Piper in London contributed to this report.