[arcatech]

The article states that it was NOT forbidden to kill civilians. Or at least, the US considered it justified.

[chubot]

the US considered it justified

s/ the US / "some bureaucratic process within the military"

which is almost certainly politically influenced, as many decisions at this level are

In this case, I don't think the bureaucracy reflects the will of the people

[impossiblefork]

The US has signed treaties according to which it is forbidden and these treaties are additionally so special that they're treated as applying to even non-signatories, the so-called customary international law.