The US military has apologised for threatening to deploy a stealth bomber on millennials who had been planning to “storm” the Area 51 test base in the Nevada desert.

Over the weekend, an estimated 150 people descended on the highly secretive base, about two hours drive from Las Vegas, which has long been a magnet for UFO enthusiasts convinced that it housed aliens from outer space.

Thousands had been expected after a student created a Facebook page in June called “Storm Area 51, They Can’t Stop All of Us”.

The page became a viral sensation with more than three million people expressing an interest in turning up to “see them aliens”.

On Friday, fearing a mass invasion, the Defence Visual Information Distribution Service (DVIDS) - the US military PR arm - posted a picture of service personnel standing by a B-2 stealth bomber alongside the caption: "The last thing #Millennials will see if they attempt the #area51raid today".

In reality, the feared flood of alien-spotters turned out to be little more than a trickle of eccentrics in an eclectic array of costumes who were an irritant rather than a danger to national security.