US Military chiefs, keen to intimidate Russia during the Cold War, plotted to blow up the moon with a nuclear bomb, according to project documents kept secret for for nearly 45 years.

The army chiefs allegedly developed a top-secret project called, 'A Study of Lunar Research Flights' – or 'Project A119', in the hope that their Soviet rivals would be intimidated by a display of America’s Cold War muscle.

According to The Sun newspaper the military bosses developed a classified plan to launch a nuclear weapon 238,000 miles to the moon where it would be detonated upon impact.

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The planners reportedly opted for an atom bomb, rather than a hydrogen bomb, because the latter would be too heavy for the missile.

Physicist Leonard Reiffel, who says he was involved in the project, claims the hope was that the flash from the bomb would intimidate the Russians following their successful launching of the Sputnik satellite in October 1957.

The planning of the explosion reportedly included calculations by astronomer Carl Sagan, who was then a young graduate.

Documents reportedly show the plan was abandoned because of fears it would have an adverse effect on Earth should the explosion fail.

The scientists were also, reportedly, concerned about about contaminating the moon with radioactive material, Mr Reiffel said.

The US government has never formally confirmed its involvement in the study.