Zhu, an expert in political science and worldwide relations, did not expect North Korea to be diplomatically engaged with other nations during the games.
What happened at the dinner?
Up the road, however, an elderly husband and wife, each draped in the South Korean flag, denounced Moon as a "fake president".
"The one thing you can say is communication has opened up to the highest levels between the South Korean and North Korean regimes".
International Olympic Committee president Thomas Bach addressed the stadium, calling on all at the Games to take inspiration from what they had just witnessed. The Tongan was touted as the hero of the opening ceremony at Rio 2016, when he entered the - considerably warmer - stadium shirtless while waving the flag of his nation.
But all eyes are on Yo Jong - a key member of the Kim dynasty that has ruled the impoverished, isolated nation with an iron fist and pervasive personality cult over three generations.
She is on a U.S. sanctions list over alleged links to human rights abuses in North Korea.
Senior Oxfam staff took part in "Caligula-style" orgy
It dismissed four staff members while a further three, including van Hauwermeiren, resigned before the investigation concluded. None of the accused from the report have faced any criminal charges.
The journey to PyeongChang started four years ago in Sochi.
Kim Jong Un's sister arrived at a train station Friday morning. She is expected to sit down for lunch with Mr Moon at the presidential Blue House in Seoul. And female ice hockey players from both Koreas will compete as one team.
It cemented what has been a rapid improvement in Korean ties since North Korea - after months of fierce nuclear rhetoric and missile tests - agreed last month to attend its first Olympics in the South.
South Korean hockey player Park Jong-ah and North Korean hockey player Jong Su-hyon basically completed the hardest leg day ever in front of the entire world when they climbed the huge set of stairs up to the torch in flawless unison, and people were seriously impressed. Its delegation includes government officials, athletes, artists and cheerleaders. Some details of the opening ceremony remain closely guarded secrets, but expect a celebration of Korean culture and history.
Experts have cautioned that the current burst of sports diplomacy does not put an end to underlying regional tensions.
South Korea treated the ferry as an exception to maritime sanctions it imposed on the North so it could transport the artists to the South.
Nevertheless, 2018 has got the countries off on an improved footing.
The South had already said the North would be welcome to send a delegation, but few believed it would happen.