US and coalition airstrikes against the northern Syrian villages of Tokhar and Hoshariyeh have killed at least 56 civilians, including 11 children, according to the Syrian Observatory for Human Rights. Other groups claimed the civilian toll was as high as 200.

The villages are ISIS-held villages near the city of Manbij, which US-backed rebels are attacking. This civilian toll comes less than 24 hours after an incident in which US airstrikes against Manbij itself killed 20 civilians,

The village attacks, however, have really raised eyebrows, and as the death toll is still getting sorted out, it could well stand as the deadliest US coalition attack on civilians in the entire war.

The Pentagon rarely accounts for civilians killed in airstrikes in Iraq and Syria, occasionally issuing statements with dramatic undercounts of the number of civilians they’ve killed since the war began. US attacks in and around Manbij alone had killed over 100 before the village incidents.

The increased death tolls come after an April decision to dramatically expand the rules of engagement, and introduce a “sliding scale” of the number of civilians US forces are allowed to kill based on the target of the attack. The rules broadly remain secret, and it’s unclear if the 56 killed today, or the 20 killed yesterday, would be considered “acceptable” according to them. The Pentagon did, at the very least, admit that they were looking into the matter, which is farther than many get.