But the North was still welcomed with open arms to what South Korean President Moon Jae-in called "Olympic games of peace" and the US appeared to be the one left out in the cold.
The invitation came during talks and a lunch Moon hosted with Kim Yo Jong, the younger sister of the North Korean leader, at the presidential Blue House in Seoul.
Kim Yo Jong arrived in South Korea on Friday with Kim Yong Nam, the North's nominal head of state, for the opening ceremony of the Winter Olympics in the alpine resort town of Pyeongchang.
The vice president will move to the country's eastern alpine town of PyeongChang later in the day to join the opening ceremony of the Winter Olympics, which will be held from Friday through February 25.
The nuclear-armed North's delegation is the diplomatic highlight of an Olympics-driven rapprochement on the divided peninsula.
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The Saint Petersburg forum, an annual summit of business leaders and politicians, has taken place for more than two decades. Syria has been gripped by a new and escalating round of violence in recent weeks.
While Moon did not hesitate to shake hands and smile with his North Korean visitors, Pence didn't appear to even look in the direction of the North Korean delegation during the Friday event.
It's the final stop on a six-day trip that Pence had hoped would increase pressure on North Korea as it seeks to use the games to pursue an opening with the South.
Moon is desperate to use the games as an opportunity to restore regular communication with North Korea and eventually pull it into talks over resolving the global stand-off over its nuclear program.
U.S. Vice President Mike Pence and South Korean President Moon Jae-in are speaking while watching Olympic speedskaters compete, hours after Moon received a historic invitation to visit North Korea.
North Korea has sent some of the highest level officials ever to the south for these games, the result of diplomacy by Seoul that led to an agreement between the two countries - still formally at war - to participate together in the Winter Games.
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In a letter to the head of Iranian convoy to the 2018 Olympic Winter Games, the committee officially apologized over the move. No reason was given, but Internet access is strictly limited in the North.
Kim Jong Un wanted to meet Moon "at an early date", a spokesman for the Blue House said.
Tensions between the two soared past year as Pyongyang tested missiles capable of reaching the US mainland and its most powerful nuclear device to date, while Kim Jong Un and US President Donald Trump traded personal insults and threats of war.
But South Korea's presidential Blue House said Mr Pence had a meeting scheduled with U.S. athletes and had only planned to stay briefly to greet other officials. Athletes from the two countries marched side by side during the opening ceremony and have formed a joint women's hockey team.
Saturday's meeting also involved two other high-level delegates - Choe Hwi, the chairman of the National Sports Guidance Committee, and Ri Son-gwon, the head of the North's state agency in charge of inter-Korean affairs.
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A spokesman from the bus company, The Kowloon Motor Bus company, said HK$80,000 (£7,300) would be paid to each victim's family. The police said that they will need to expand the road blog and send more personnel to the scene for the investigation.