In a landmark visit, a high-level North Korean delegation, including leader Kim Jong-un's younger sister has arrived in South Korea in the face of the opening ceremony of the 2018 Pyeongchang Winter Olympics.

Kim Yo Jong's arrival at the Incheon airport on Friday marked the first time a member of North Korea's ruling family has crossed the border since the 1950 Korean War.

Arriving on her brother's private jet for a three-day visit, Kim Yo Jong and the country's 90-year-old nominal head of state Kim Yong Nam are scheduled to meet South Korean President Moon Jae-in on Saturday in a luncheon at Seoul's presidential palace.

The North Korean delegation also includes Choe Hwi, chairman of the country's National Sports Guidance Committee, and Ri Son Gwon, chairman of the North's agency that deals with inter-Korean affairs.

Both North and South Korea are due to march together under a "unification flag" at the opening ceremony on Friday.

Meanwhile, Japanese Prime Minister Shinzo Abe has also arrived in South Korea.

Before departing for Pyeongchang, Abe said co-operation between Japan, the US and South Korea on North Korea's nuclear threat remained strong.

Thaw in ties

There has been an apparent thaw in relations between North and South Korea in recent weeks.

The two neighbours resumed cross-border talks last month.

In what was described as a major diplomatic breakthrough, North Korea said it would send a delegation of athletes and performers to the Pyeongchang Winter Olympics in South Korea.

North Korea staged a relatively toned down military parade to mark the 70th anniversary of its armed forces in its capital on Thursday.

"North Korea and South Korea are in a period of major overtures," said Al Jazeera's Natasha Ghoneim, reporting from the South Korean city of Gangneung,

"There has been a thaw in the relationship and a real hope that the Pyeongchang Winter Olympics will be a moment of true reconciliation and peace."

The Pyeongchang Winter Olympics will be held from February 9 to 25.