SEOUL, South Korea (NYTIMES) - In the highest-level contact between the two Koreas in years, President Moon Jae-in of South Korea plans to meet on Saturday with the sister of the North Korean leader, Kim Jong Un, and the North's nominal head of state, officials said on Thursday (Feb 8).

Moon's luncheon meeting with the North Koreans was announced on Thursday, as Vice-President Mike Pence arrived in South Korea carrying a message from Washington: not to waver from strong sanctions against North Korea.

The high-level North Korean delegation, headed by Kim Yong Nam, the North's ceremonial head of state, will arrive in South Korea on Friday on a special plane to attend the opening ceremony of the Winter Olympics later in the day.

The trip's significance was underscored by the revelation on Wednesday that the delegation would include Kim Yo Jong, the only sister and a trusted aide of Kim Jong Un, the North's supreme leader.

In North Korea's dynastic system, which upholds the Kim family's "bloodline" as a sacred leadership qualification, Kim Yo Jong wields a singular clout that cannot be matched by any nonrelative members of the elite, regardless of their official titles, according to North Korea analysts.

Kim Yo Jong would be the first member of North Korea's ruling family to visit the South since the 1950-53 Korean War.

In 2000, her father, Kim Jong Il, held a summit meeting in North Korea with Kim Dae-jung, then South Korea's president, but did not keep his promise to visit for a second meeting. Kim Jong Il died in 2011, bequeathing power to his third son, Kim Jong Un, who has rapidly accelerated the North's weapons programmes.

Pence met with Moon on Thursday, and both reaffirmed a principle of "using maximum sanctions and pressure to bring North Korea to the negotiating table for denuclearisation," said Moon's spokesman, Yoon Young-chan.

Moon again emphasised the need for talks with North Korea, saying that he hoped that the inter-Korean dialogue started by the North's participation in the Olympics would lead to broader talks on resolving the North Korean nuclear crisis, Yoon said.