The US Central Command on November 14 said a 2019 airstrike that killed civilians in Syria was “legitimate”, after a New York Times (NYT) investigation said the military had concealed the death of dozens of non-combatants.

The newspaper published the results of its investigation on November 13 saying a US special task force operating in Syria – sometimes leaving its military partners in the dark to preserve secrecy – dropped three bombs on a cluster of civilians near the Islamic State (IS) group bastion of Baghouz, killing 70 people, mainly women and children.

The report says a US legal officer “flagged the strike as a possible war crime” but that “at nearly every step, the military made moves that concealed the catastrophic strike”.

Drawing from confidential documents, interviews with personnel directly involved and officials with top security clearance, the NYT found that the strike “was one of the largest civilian casualty incidents of the war against the Islamic State”, albeit never publicly acknowledged by the US military.

“The death toll was downplayed. Reports were delayed, sanitised and classified. United States-led coalition forces bulldozed the blast site. And top leaders were not notified,” the report said, adding the Pentagon’s independent inspector general’s probe findings were “stalled and stripped of any mention of the strike”.

In a detailed response, Central Command (Centcom) said an investigation found the strike was “legitimate self-defence”, “proportional” and that “appropriate steps were taken to rule out the presence of civilians”.

It added an investigation was launched after a military report found there had likely been civilian casualties.

Along with 16 IS fighters determined to have died in the bombing, the investigation concluded at least four civilians were killed and eight wounded.

“We self-reported and investigated the strike according to our own evidence and take full responsibility for the unintended loss of life,” said Centcom spokesperson Captain Bill Urban.

He said the investigation could not “conclusively characterise the status of more than 60 other casualties”, adding that some women and children, “whether through indoctrination or choice, decided to take up arms in this battle and as such could not strictly be classified as civilians”.

Kurdish-led Syrian Democratic Forces (SDF) and their US-led coalition allies declared the defeat of a self-proclaimed IS “caliphate” in March 2019 after years of fighting culminated in ousting jihadists from their last Syrian stronghold in the eastern village of Baghouz.

According to the NYT, the strike was carried out despite the presence of civilians by the special operations unit “Task Force 9” after a request from the SDF and ignoring military directives in place to protect civilians.

Each bombardment was meant to be preceded by checks, sometimes lasting days or weeks.

But “over time, some officials overseeing the air campaign began to believe that the task force was systematically circumventing the safeguards created to limit civilian deaths”, the report said.

On March 18, 2019, Task Force 9 circumvented oversight by reporting imminent danger and invoking self-defence, as in many other strikes during this conflict, according to the NYT.

Urban that morning said “an SDF position under heavy fire and in danger of being overrun called for defensive airstrikes on Isis fighter positions”, adding that the SDF and on-the-ground special operations forces reported no civilians in the area.

The investigation determined that no disciplinary action was required after the bombing, but that it led to new requirements for high-definition video for future, similar strikes and further coordination with “surveillance assets” in the strike area.