Army chiefs were urged to fight aliens with nukes, according to a secret document.
UFO hunters have got their hands on a once secret report called 'Extra-Terrestrial Warfare' by the Combat Operations Research Group.
It sets out how the US Army would need to prepare for war with Martians.
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But they would have to develop new weapons, vehicles and moon bases to take on hostile ETs.
The opening page states: "The United States may be called upon to wage extra-terrestrial warfare within the next two to three decades.
"This paper explores the implications of this requirement for the US Army and proposes a program of studies that will enable the Army to meet this requirement."
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