Preparing for the worst How to escape from Kim Jong Un

It's a bitterly cold, bleak day on a military base in South Korea.

People are milling around calmly, clutching hot coffees, making small talk. Kids are chasing each other around an air hangar.

It's hard to believe they are practicing a high-stakes emergency evacuation that simulates what would happen if North Korea invaded.

"In real life, everyone would be wearing masks, rushing through places," says mom of two Nicholle Martinez. "There would be chaos everywhere. It would be scarier."

Nicholle met Nick Martinez when they were both stationed with the US military in Seoul. They've now been married for nine years and have two beautiful, energetic and charismatic children. Briannah, 6, is in first grade, and Alannah, 8, is in third.

In many respects they're very typical. They go to church on Sundays and have lunch together afterward. They like to play sports -- mom and dad want the girls to grow into healthy, strong young ladies.

Briannah wants to be a teacher, Alannah wants to be president.

But, because the whole family is now living on post in Seoul, the Martinez family lives with the ever-present danger of a very noisy and unpredictable neighbor -- Kim Jong Un.