South Korea's Amry Special Warfare Command (SWC) soldiers aim their machine guns in a frozen river during a winter exercise in Pyeongchang, South Korea, Thursday, January 8, 2015. About 200 SWC soldiers participated in this routine two-week winter drill. (Photo by Ahn Young-joon/AP Photo)

Shirtless members of the South Korean Special Warfare Forces hurl snow during a winter exercise in Pyeongchang January 8, 2015. North Korean leader Kim Jong Un said there was “no reason” not to hold a high-level summit with neighbouring South Korea, speaking in a New Year's address broadcast by state media last Thursday. (Photo by Kim Hong-Ji/Reuters)

Members of the South Korean Special Warfare Forces take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

A member of the South Korean Special Warfare Forces takes his position in frozen waters during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Members of the South Korean Special Warfare Forces take their positions in frozen waters during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

A member of the South Korean Special Warfare Forces takes his position in frozen waters during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Members of the South Korean Special Warfare Forces take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Members of the South Korean Special Warfare Forces holding combat knives take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Members of the South Korean Special Warfare Forces holding combat knives take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

A sniper from the South Korean Special Warfare Forces takes aim with his rifle during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

A member of the South Korean Special Warfare Forces takes his position during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Shirtless members of the South Korean Special Warfare Forces take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Shirtless members of the South Korean Special Warfare Forces take part in a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Shirtless members of the South Korean Special Warfare Forces hurl snow during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

Shirtless members of the South Korean Special Warfare Forces run during a winter exercise in Pyeongchang January 8, 2015. (Photo by Kim Hong-Ji/Reuters)

A South Korea's Amry Special Warfare Command (SWC) soldier takes his position while others rappel from a helicopter during a winter exercise in Pyeongchang, South Korea, Thursday, January 8, 2015. (Photo by Ahn Young-joon/AP Photo)

South Korea's Amry Special Warfare Command (SWC) soldiers attend a winter exercise in Pyeongchang, South Korea, Thursday , January 8, 2015. (Photo by Ahn Young-joon/AP Photo)

South Korea's Amry Special Warfare Command (SWC) soldiers demonstrate their martial arts skills during a winter exercise in Pyeongchang, South Korea, Thursday , January 8, 2015. (Photo by Ahn Young-joon/AP Photo)