What if something akin to the 9/11 attacks had taken place during the Cold War? Would the United States be better prepared to defend against the threat and perhaps even intercept some of the airliners before they hit their targets? Alternatively, might a combination of alternate target selection (SAC headquarters, for example) and the environment of the Cold War lead some to conclude that it's the opening wave of a strategic nuclear strike, leading to the declaration of an Air Defense Emergency (and thus DEFCON 1 for all forces), potentially leading to nuclear war?