In a rare public criticism of Saudi Arabia, Lt. Gen. Jeffrey Harrigian called on the Saudi-led coalition to be more transparent with their investigation into an airstrike earlier this month against a school bus in the Saada Province of Yemen. The attack killed at least 42 children.

Harrigian said there is a “level of frustration we need to acknowledge” and that they further need to be clear what happened and why. The US hasn’t exactly been forthcoming in its own involvement in the attack either, saying they were uncertain if a US bomb was used right up until media agencies showed pictures of the Lockheed Martin bomb.

Unlike other recent incidents where they killed scores of civilians, the Saudis already made a statement on this attack, declaring the school bus to be a “legitimate military target.” They did not explain why.

This raises questions about whether an investigation is ongoing at all, as even the cursory whitewashing reports the Saudis offer for other incidents are usually the end result of strikes they denied or claimed uncertain about. In this case, they’ve insisted from the start the destruction of the bus was by design.

Not that the call for transparency really means anything to US policy. Secretary of Defense James Mattis says that since one Saudi general described the deaths as “tragic,” the US appreciates that there isn’t “callous disregard,” and therefore US military support for the war continues.