Security drills in Pyeongchang as South Korea prepares for Olympics

(CBS) -- A terrorist has taken athletes hostage and is about to ram a vehicle into an Olympic stadium. A chemical bomb explodes in a trashcan as spectators run for their lives, and a drone carrying explosives is shot out of the sky. These are just some of terror drills security forces have been conducting near Olympic sites.

A law enforcement command center is now open in Pyeongchang to monitor security during the games. Overall, South Korea is mobilizing a more than 60,000 person Olympic security force, including 50,000 soldiers.

That includes South Korean marines who, in a somewhat odd display with their American counterparts, tested their tolerance for the cold and snow.

"We've covered reconnaissance skills as well as critical combat skills in a cold weather mountainous environment," says Captain Thomas Rigby, with the U.S. Marine Corps.

Of course, one of the biggest concerns is North Korea.

In 1987-ten months before South Korea held the summer Olympics in Seoul-North Korean agents placed a bomb on a Korean Air flight, killing all 115 people onboard. Kim Jong-un's rogue nation is just 50 miles from Pyeongchang

The U.S. and South Korea delayed their annual military exercises so as not to provoke North Korea. The North's decision to send a large delegation to the games is thought to have reduced the chances that it will disrupt the event with a missile launch or nuclear test.

Another concern at the Olympics is some sort of massive cyber attack that could disrupt the games. North Korea is well known for its cyber warfare skills. They have hired a private cybersecurity firm to try to prevent that kind of attack.