Nuclear security

See the US nuclear weapons 'hidden in plain sight' as North Korea tensions rise

The missiles themselves sit underground in concrete silos.

The Minuteman 111 missile is 20 times more powerful than the bomb dropped on Hiroshima more than 70 years ago, and can hit a target anywhere on the globe within 30 to 40 minutes.

And its impact?

"We don’t know [the level of destruction if a missile is launched] but we do know from history that it is devastating. I think there is no doubt that we're looking at millions of people whose lives will be impacted from these nuclear weapons.”

Tomorrow, troops from the US, South Korean and Australia will take part in military exercises on the Korean Peninsula, which is bound to aggravate the highly unpredictable North Korean leader.

"Leon Panetta makes the point [that] we actually don't know enough about Kim Jong-un to know whether he will be the kind of guy who will spontaneously combust," Hayes says.