5. Furtherance
Up until 1968, there was a plan in effect in the USA called Furtherance. Furtherance stated that if the US president was killed in an attack, the USA would launch an automatic, all out attack on both the USSR and China - even if the president was killed by conventional means or as a result of an accident. Lyndon B Johnson updated the plans in 1968 making them more flexible and discriminatory. Different countries could be targeted and there was a delineation between the USSR and China and scope for a limited attack rather than full on Mutual Assured Destruction. Was this realisation of nuclear stalemate in Russia? That she was a less formidable opponent? In the wake of international terrorism, there are further Continuity of Government policies to protect the USA President and his Chain of Command. However, Furtherance remains a terrifying historical document and it shows us in retrospect how serious the Cold War was - something that we tend to forget nowadays. The US had plans to bomb the entire Communist world - even in a conventional war, if the President was killed. And given that tensions were frequently high (The Cuban Missile Crisis) there were times in the Cold War that this could have happened, or arena conflicts, like Vietnam, could have escalated into Hot War between East and West, Furtherance had the potential for the whole world to combust.