If that were the case then we wouldn't be here discussing this because we (or at least our parents) would've all been blown to smithereens in the Cold War. The Cuban Missile Crisis is an example of how the "shoot first ask questions later" policy would've started World War 3. Had Kennedy decided to invade Cuba instead of merely blockading them, the Soviets would have launched their missiles at us.

Intelligence is always up to the intepretation of the CIA, and it's often out of context and far from complete. I don't think Bush should be penalized for acting on faulty intelligence, but I think in this case he could've acted with much more finesse and diplomacy.