The spectre of nuclear annihilation looms over millions of South Koreans’ lives every day, but the added spotlight of the Olympic Games has intensified safety concerns should the North ever launch an attack.

Defence experts have said many times over the years that a direct nuclear strike on the capital of Seoul would likely kill the vast majority of its nearly 10 million inhabitants. However, that hasn’t deterred Seoul’s citizens from taking many precautions against a catastrophic attack by North Korea, whether nuclear or otherwise.

Seoul’s subway stations, for instance, have been reinforced to shelter the nearly 9 million commuters who use the service every day. The bunker-like stations are designed to withstand non-nuclear attacks, and are even equipped with vending machine-sized cabinets containing water, rations and gas masks. However, some have pointed out that these cabinets do not contain nearly enough supplies to support hundreds or thousands of South Koreans in the event of a crisis.

Disaster preparedness has become a highly lucrative business in Seoul, where gas mask and ration sales spike every time Kim Jong Un threatens the South. Each threat typically drives a 30-40 per cent increase in sales.

The latest case of North Korean sabre-rattling came Thursday, when Kim Jong Un presided over a military parade in Pyongyang.

South Korea will host many foreign dignitaries during the Games, including U.S. Vice President Mike Pence. That might make it sound like a good time for North Korea to attack, but the North also has a vested interest in keeping the peace during the Games. Kim Jong Un has sent a contingent of athletes and cheerleaders to Pyeongchang, with his sister, Kim Yo Jong, at their head. She will be the first member of the Kim family ever to visit the South.

The 2018 Winter Games open in Pyeongchang Friday.

With files from CTV National News correspondent Peter Akman

This video from CTV's Mark Khouzam shows North Korean cheerleaders walking into the Athletes Village: