In South Korea, Pence will visit a memorial to the 46 South Korean sailors killed in a 2010 torpedo attack attributed to the North, and hold meetings with President Moon Jae-in.
Security issues topped the agenda at Wednesday's meeting here between U.S. Vice President Mike Pence, who was on his way to the Pyeongchang Games, and Japanese Prime Minister Shinzo Abe. USA officials declined to provide details of the expected sanctions.
South Korean President Moon Jae-in told his USA counterpart Donald Trump in a phone call on Friday that the momentum of improved North-South relations would continue and that Pence's visit would be an "important prelude for that", according to the Blue House. Depending on what's on display, and whether it's real, it could also mark the transformation of Kim Jong Un's patchy nuclear missile program into a legitimate threat.
South Korea's Unification Ministry said in a statement that Kim Yo Jong will be joining North Korea's high-level delegation to the South, headed by Kim Yong Nam, president of North Korea's parliament.
Kim Yo Jong would be the first member of the Kim family, born on the sacred Mount Paektu, which is a centerpiece of the North's idolization and propaganda campaign, to cross the border to the South.
But Kim has taken a more conciliatory tone in 2018, calling for detente with the South Koreans and accepting an invitation for his country to participate in what is being billed as the "peace Olympics". He also said Washington may see Kim Yo Jong as an avenue to deliver messages to Kim Jong Un. Reid Feist has more from South Korea. "But with Kim Yo Jong, you are getting a person who's chiefly involved in designing Kim Jong Un's rule, a person whom the leader actually listens to".
Born September 26, 1987, Kim Yo Jong studied in Switzerland like her brother and is believed to have attended Kim Il Sung University and a western European school for her higher education.
Indeed, she'll want to keep on her brother's good side, if the fate of their half-brother Kim Jong Nam is anything to go by.
The profile of Kim Yo-Jong has been elevated since 2014 when she was appointed vice-director of the party's propaganda and agitation department, according to an October 2017 report by Geostrategy-Direct.
Tensions soared a year ago as the North carried out multiple weapons tests, including intercontinental ballistic missiles capable of reaching the United States mainland, and by far its most powerful nuclear test to date.
The US and North Korea have been locked in a fierce war of words.
While publicly supportive of the North-South talks over the Olympics issue and the subsequent cooperation, the USA is wary of allowing North Korea's government to gain economic concessions from the south through its so-called "charm offensive".
"Congratulations to the Republic of Korea on what will be a MAGNIFICENT Winter Olympics!" he wrote.
The White House said in a statement that the Pences' presence at the Olympics will "reinforce the strong US presence on the Korean Peninsula and send a clear message of American resolve to the North Korean regime".
Abe and Pence on Wednesday reaffirmed the importance of exerting maximum pressure on North Korea.