It's only a violation of the First Law if you directly kill them with magic.
There's a fair amount of textual evidence that actually binding creatures and ordering them to kill also counts. Hence Morgan in Storm Front.
Gas chambers, however, do not.
On the other hand, barring violating the Laws, individual White Council members have no restrictions on their behavior...so blowing up Nazis with improvised explosives planted while Veiled is fine. So is slitting the commander's throat with a dagger after knocking him out with a purely physical sleep spell. And none of it will piss off the Council in the least. The Laws exist at least partially to keep Wizards from interfering with mortal governments and organizations
too much...but there's no Law against interference per se.