Norman Geras says, in the course of writing about Bush’s war:
To give a crude analogy here: if someone burgles a house and her only motive in doing so is greed, I will approve of her action if, in order to bring off the burglary, she finds she has to release a terrified family from the grip of a bullying, violent and child-abusing patriarch. I will not think that what happened was overall bad because it was – ‘in essence’ – a burglary; or worry, in my approval, about the burglar going on to burgle others. If she does, we can disapprove of – and oppose – that.
Whereas I don’t think, to give another crude analogy here, that a mob war should be thought of as a public service, even if it clears the streets of some deserving scumbags.