After thinking about it, I'm not sure what would have been the right move.

Advanced notice gives the planners/higher-ups in the "organization" time to slip away, while their followers stay behind to fight.

Not giving advanced notice could have led to excessive civilian deaths and a backlash from the civilian residents of the city.

It's sure been ugly in the region in the last couple weeks, though. I'd hate to be the one to formulate a strategy at this point.
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She was standin' alone over by the juke box, like she'd something to sell.
I said "baby, what's the goin' price?" She told me to go to hell.

Bon Scott - Shot Down in Flames