A six-week investigation by the U.S. Air Forces Central Command concluded that jets operated by the anti-Islamic State coalition mistakenly struck forces likely aligned with the Syrian government in September, and blamed the incident on "human error."
Investigators could not confirm that the personnel and vehicles targeted in the Sept. 17 strikes belonged to the Syrian military because the forces were not wearing uniforms and displayed no insignia or flag denoting their affiliation.
Brig. Gen. Richard Coe, the lead investigating officer, briefed reporters on the investigation's findings and recommendations on Tuesday morning, explaining that a series of human errors during the targeting process resulted in planners mistakenly identifying the targets as ISIS militants.
"In this incident, ultimately we made an unintentional, regrettable error primarily based on human factors in several areas of the targeting process," Coe told reporters.
Forces with the U.S.-led coalition launched strikes on what they believed were ISIS targets near Dayr az Zawr in Syria on Sept. 17. The strikes were immediately halted when Russian personnel told coalition officials that the personnel and vehicles being targeted were part of the Syrian military.
Gen. Joseph Votel, the commander of U.S. Central Command, directed an investigation into the strikes after reports indicated that dozens of Syrian forces had been killed.
Over the course of six weeks, investigators interviewed more than 70 U.S. and coalition personnel and reviewed intelligence reports, imagery, tactical and legal guidance, and the targeting process used in the strikes. Officials from Australia, Denmark, and the United Kingdom aided the investigation because their countries' forces were also involved in the strikes.
The Central Command investigation, the full report of which is classified, concluded that the forces struck were "likely" aligned with Syrian dictator Bashar al Assad.
"Since the forces they were observing during the strike were not wearing uniforms, they had no flags or insignia, we could not attribute a unit or whether specifically they were Syrian regime military," Coe told reporters on a phone call. "We believe those forces were aligned with the Syrian regime more likely than not."
Several factors led coalition planners at the Combined Air Operations Center to misidentify forces on the ground as ISIS, such as the forces' lack of uniforms and "very friendly" interaction with individuals in an ISIS area of influence. The planners lacked knowledge of the terrain around Dayr az Zawr compared with other areas in the region.
Early on, planners mistakenly determined that a vehicle was operated by ISIS forces—a "significant contributing factor" in the resulting mistake, according to Coe. The vehicle eventually drove into the area targeted in the airstrikes.
The investigation found problems with the "hybrid" process of dynamic and deliberate targeting used during the strikes. Officials are currently conducting a full review of the process.
"Our impression was there were good people trying to do the right thing. These people get it right far more often than not, but this time they came up short," Coe said. "The mistakes that happened do not stem from negligence or malice. They stem from a series of unintentional human errors, but we do hold ourselves to the highest of standards and we must do better."
Coe emphasized that the targeting decision was made in good faith, and in compliance with the law of armed conflict and applicable rules of engagement.
The probe also found that the Russians called to inform coalition forces that the personnel they were targeting belonged to the Syrian military, but waited 27 minutes to pass on the information because they wanted to speak to the traditional point of contact. Fifteen of the 32 strikes occurred during this 27-minute period.
"That critical safety information could be passed immediately rather than waiting for the traditional POCs," Coe said. The Combined Air Operation Center has since told the Russians that they should convey critical information without delay.
Coalition forces notified the Russians of the planned strike over a safety hotline in order to avoid air accidents in the area. However, the officials unintentionally gave the Russians inaccurate coordinates when describing the planned strikes, a mistake that, if avoided, could have resulted in more rapid notification from the Russians that they had mistakenly targeted non-ISIS forces.
Russia claimed that the airstrikes killed 62 Syrian government troops and wounded over 100. The Syrian Observatory for Human Rights later reported that 83 individuals were killed. The Central Command probe only substantiated 15 deaths, though Coe said investigators "believe" there were more casualties.
The airstrikes took place during a fragile ceasefire between Syrian regime and rebel forces brokered by the United States and Russia. The ceasefire was repeatedly violated and collapsed after seven days after Russian and Syrian jets bombed rebel-held areas of Aleppo. Russia said the Sept. 17 strikes jeopardized the ceasefire.
Two days after the mistaken airstrikes, a U.S. convoy in Syria was bombed when delivering humanitarian aid in a rebel-held town outside Aleppo, which the United States believes was the work of Russian warplanes. Moscow has denied the charge.
Russia began bombing targets in Syria last September in what it claimed were efforts to help Assad's forces fight ISIS. However, Russian jets have repeatedly bombed areas not under ISIS control, targeting U.S.-backed rebels fighting the Assad regime.
Diplomatic efforts by the Obama administration to cooperate with Moscow to end the five-year Syrian civil war and deliver humanitarian aid in the war-torn country have been unsuccessful. The civil war has killed an estimated 400,000 Syrians, according to a U.N. estimate disclosed in April.