"A government is an institution that holds a monopoly on the legitimate use of violence."

• Max Weber

Politics and violence cannot be separated. The only relevant factor is "legitimacy", which is determined politically.

At what point, during the incremental rise of the Nazis, would it have become "legitimate" to take action against them, and how would this legitimacy be determined? Too early, and it would have been seen as illegitimate murder or "political violence" - too late and... Well, we know what happened.