The decision came after a New York Times investigation found that the US military tried to hide the 2019 Syria strike, which killed at least 70 civilians, including women and children.
The Pentagon has launched a fresh probe into a 2019 air strike that killed civilians in Syria, two weeks after a New York Times investigation claimed the US military concealed dozens of non-combatants' deaths.
Defence Secretary Lloyd Austin instructed Army General Michael Garrett to "review the reports of the investigation already conducted" and "conduct further inquiry into the facts and circumstances related to it," Pentagon spokesman John Kirby said on Monday.
Garrett's three-month review will assess "civilian casualties that resulted from the incident, compliance with the law of war, record keeping and reporting procedures," he added.
It will also probe whether measures taken after the earlier investigation were effectively implemented, if "accountability measures" should be taken and if "procedures or processes should be altered."
'One of the largest civilian casualty incidents'
According to a Times investigation published mid-November, a US special force operating in Syria bombed a group of civilians three times on March 18, 2019.
The attack near the Daesh bastion of Baghouz, killed at least 70 people, mainly women and children.
The Times 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."
The Times found the strike "was one of the largest civilian casualty incidents" during the battle against Daesh, but was 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 findings of a Pentagon probe were "stalled and stripped of any mention of the strike."
A statement released by the Pentagon after the report said the initial investigation into the incident found the strikes were "self-defense," "proportional".
This report by the US Army Central Command, which oversees military operations in the Middle East, also stated "appropriate steps were taken to exclude the presence of civilians."