Dedicated to the Cold War, the Minuteman Missile US historic site gives visitors a glimpse into the reality of life under the threat of nuclear war.

Pierre, South Dakota - This is probably the only museum in the world where visitors are greeted with signs that threaten them with being shot.

“Everyone is welcome here, of course - but that's what it was like at the time and that's why we have to have the signs here,” says Alison Shoup, head of a South Dakota museum with a difference.

Dedicated to the Cold War, the Minuteman Missile US historic site gives visitors a glimpse into the reality of life under the threat of nuclear war - in the former silos and command bunkers of a military unit trained to fire intercontinental nuclear missiles.

Disarmament treaties between the United States and the Soviet Union provided for both nations to dismantle them, but retain one missile silo each - as a museum.

North and South Dakota are two of the least densely populated states in the United States and in the Cold War, the region's remoteness was of strategic importance. There were more nuclear missiles here than anywhere else in the world.

“If the Dakotas were an independent country, it would have been the third most powerful nation in the world,” says Shoup. “People were driving past for decades, and had no idea they were surrounded by dozens of atomic bombs,” the ranger adds.

In the case of war, lids would have come off holes in the prairie to launching deadly missiles towards the Soviet block from the bunkers.

“That's exactly what we want to remember. How people lived here at that time and what kind of danger we were all in,” says Shoup. Most of the tourists arrive in a jolly, holiday mood.

“But when they leave they're a lot quieter. And a lot of the time I hear people say 'Thank God it never got serious.'

“We've been around since 1999, but until now it's been more of a makeshift kind of museum,” says Shoup. “But even so, we've still had 50 000 visitors a year. Now we have a visitor's centre and a professional exhibition. And we're being bombarded with people.”

She says the number of visitors has tripled since the improvements to the exhibition.

The Minuteman II missile was revolutionary at the beginning of the 1960s. It was smaller, safer and cheaper than its predecessor - but just as deadly.

The facility looked like a farm house from the outside, and it still does. But just 10 metres underground, the entrance to the control room is hidden away behind an 8-ton steel door more than half a metre thick.

“This was a place where people could lock themselves away. But they wouldn't have survived for long. Everything's set up so you could survive a nuclear strike from Russia. But only for long enough to respond to it.”

To fire the missile, two keys 4 metres apart from each other would have had to be turned simultaneously. The aim of this was to make sure no single person had the power to “push the button” so to speak.

In addition to that, there would need to be a command to fire from another bunker to confirm.

“There was a lot of thought put into safety at that time. But the situation never arose where the security measures were put to the test. Luckily!”

“5 166 miles to Moscow” reads one of the computer screens. “My cellphone has more processing power than that computer,” says one of the park rangers. But he still finds it all fascinating. He shakes his head. “And it was all made to destroy.”

The only security outside the facility was a fence along with some motion sensors.

“Back then the concept of security was somewhat different,” says Shoup. If a movement sensor rang the alarm, two soldiers would go to check it out - and usually it was just a rabbit. “But locals have confessed to us that when they were teenagers they threw stones over the fence and were just delighted when they saw the jeep coming.”

Under the ground, the commanding officer had his own suite, while the others slept four to a room. It was only in the 1980s that women were allowed in. Veterans have said that the men had no problem with women suddenly working there. But perhaps their wives weren't thrilled with their husbands spending three days shut in a bunker with other women.