That doesn't sound completely correct to me. How many people out of a million US citizens would intentionally order a strike on a school filled with children? I like to think the answer is at or near enough to zero.

I don't really find it plausible that there are enough samples in the powerful people to uncover a chain of command that all agree to intentionally murder school children.

The most likely explanation is this was a mistake. But that doesn't absolve anyone from punishment in my view. It should be almost impossible to make a mistake of this magnitude when you're dealing with weapons of mass death, and you should be culpable for the ones you do make.