North Korean leader Kim Jong-un's sister will be attending the Winter Olympic Games. Kim Yo is one of her brother's closest aides and will be the first immediate Kim family member to cross the border. Both Koreas will march united under one flag at the opening ceremony in Pyeongchang on Friday. However, some have accused the North of using the Games for propaganda purposes. US Vice President Mike Pence has been speaking in Tokyo before he heads to Pyeongchang, where he delivered a stern warning. Sung-Yoon Lee is a professor of Korean Studies at Tufts University in Massachussets, and joins Guyon Espiner to discuss the significance of North Korea's decision.