[quote=Kadaeux]
Not really. The US would have effectively annihilated itself launching the Orion. (Add in the fact it's main weapons were also it's main fuel :p). The moment the Orion began launching the USSR would have launched to eliminate it, and would have succeeded, though the US would have launched in reaction to the Soviets launching in reaction to the US's original launching. We'd have had the whole nuclear exchange. End of the world Australians conquer the Earth :p
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The status of the Soviet nuclear arsenal in the 1960s and 1970s was horrible, mostly short-range tactical nuclear missiles, bombs and a small number of primitive ICBMs. Meanwhile, the combined NATO and US nuclear missile arsenal was on the verge of being OP'd. Hundreds of highly sophisticated, ICBMs followed by tactical nuclear missiles and bombs to be used during a ground campaign.

A nuclear exchange in this time would cost around 19-20 million American lives, while wiping out most of the Soviet Union's population.

Its a crazy thing really, most of the Cold War NATO could have won, though it would have not been so pretty in the end.