Footage of hundreds of secret nuclear tests carried out during the Cold War has been declassified by the US government for the first time and placed on YouTube.

Between 1945 and 1962, the country carried out 210 nuclear tests in the Mojave desert in Nevada and on several isolated islands in the Pacific.

Concerns about nuclear fallout eventually forced them to carry out the tests either underground or high up in the atmosphere.

But as Cold War tensions rose with the Soviet Union, an arms race developed between the two superpowers as they attempted to build bigger, more deadly weapons.

The American nuclear blasts were filmed on high-speed cameras – which could capture each event at around 2,400 frames per second.

Around 10,000 of these films were sitting idle for around 65 years in a government archive but have now been restored thanks to the efforts of the Lawrence Livermore National Laboratory (LLNL), a federal research facility in northern California.

Nuclear weapons physicist Greg Spriggs and a team of film experts, archivists and software developers have now uploaded dozens of digital scans of the 750 films which were declassified for the public to view.

Dr Spriggs said they got to the project “just in time” because the films “are on the brink of decomposing to the point where they will become useless”.

The films were not scored properly at the time and are made of nitrate cellulose – which releases a vinegar smell as they degrade. This was apparent to staff when they opened the cans.

A Day That Shook The World: First nuclear submarine launched Show all 5 1 /5 A Day That Shook The World: First nuclear submarine launched A Day That Shook The World: First nuclear submarine launched 21st January 1954: The Nautilus, the world's first atomic submarine beginning her trials at Groton, Connecticut. Getty Images A Day That Shook The World: First nuclear submarine launched USS Nautilus, the world's first atomic powered submarine being launched at Groton in Connecticut. Getty Images A Day That Shook The World: First nuclear submarine launched Officers of the World's first nuclear powered vessel, the submarine USS Nautilus, stand to attention as Chief of Naval Operations Admiral Robert B Carney comes on board. Getty Images A Day That Shook The World: First nuclear submarine launched Admiral Robert B Carney observing the depth gauges of the world's first nuclear powered submarine 'Nautilus'. Getty Images A Day That Shook The World: First nuclear submarine launched A submariner puts a nickel in the jukebox on board the submarine USS Nautilus, the World's first nuclear powered vessel. The money will go toward the submarine's recreation fund. Getty Images

He said the first few years of the projects were devoted to simply finding the cans of footage. He estimates they have found 6,500 and scanned 4,200 but only analysed 400 to 500 films.

Nuclear testing was banned by a UN treaty in 1996, though it has not entered into force because it was not ratified by several states including the US.

As a result, the only data they have on high-altitude blasts comes from the 1950s tests.

Dr Spriggs said the data recorded by scientists in the 1950s was not that accurate so they are re-analysing it to create “a set of benchmark data [for use] by future weapons physicists”.

He said: “We found out most of the data which had been published was wrong and we decided we need to rescan and reanalyse all the films.