Three sources told CNN an essential signal that civilians were likely in the area and that children could be inside the target vehicle just came too late - moments after the military launched the Hellfire missile toward the target and just moments before it struck.
The precise time lapse between the missile being ejected and the intel warning of civilians in the area is not clear.
Nor is it clear if the information reached the people who gave the missile launch the green light.
Still, the report implies there may have been yet another key lapse in mind which led to the deaths of the seven children and three adults killed on August 29 in the strike, which the US military eventually admitted Friday was a "tragic mistake."
This newest report of a potential misstep by US officials comes as the grieving father of one victim charged in America "finds the person who did this" saying "I want him punished".
Emal Ahmadi, whose three-year-old daughter Malika and nine other family members were killed in the attack, told the Associated Press on Saturday that an apology is "not enough."
"That is not enough for us to say sorry. The USA should find the person who did this," he said.
Head of the U.S. Central Command Gen. Kenneth F. McKenzie Jr. announced Friday that it is unlikely any ISIS-K members were killed in a Kabul drone strike on Aug. 29, which led to multiple civilian casualties.
"We now assess that it is unlikely that the vehicle and those who died were associated with ISIS-K or a direct threat to US forces," McKenzie said of the airstrike at a briefing, following an investigation by the military.
The drone strike, which was planned to target ISIS-K operatives, resulted in the deaths of an aid worker and up to nine of his family members, including seven children. According to U.S. officials, the strike on the vehicle, once believed to have been a threat that included bombs and that was operated by ISIS-K militants, took place after a suicide bombing at Kabul airport in Afghanistan killed 13 U.S. service members and civilians.
Milley earlier this month had supported the strike, even as the details were not fully clear.
"At this point, we think that the procedures were correctly followed and it was a righteous strike," he said in a press briefing.