The US vice-president, Mike Pence, has skipped a dinner before the Winter Olympics opening ceremony, where he was expected to share a table with North Korea’s head of state, in a sign of Washington’s intention to snub Pyongyang’s officials at the Games.

Pence briefly exchanged greetings with people attending the dinner, including the South Korean president, Moon Jae-in, and the Japanese prime minister, Shinzo Abe, but avoided Kim Yong-nam, North Korea’s ceremonial head of state, highest-level official ever to have gone to the South.

North Korea’s senior diplomatic delegation, which arrived in the South on Friday, also included Kim Jong-un’s sister Kim Yo-jong, who became the first member of Pyongyang’s ruling dynasty to set foot in South Korea since the Korean war.

In an unprecedented and unexpected display of unity, Moon shook hands with Kim Yo-jong and Kim Yong-nam – a scene that would have been unimaginable a month ago. In another sign of the diplomatic rapprochement triggered by the Games, athletes from both sides of the border marched under one flag.

Pence was also sitting in the VIP section, metres from the North Korean officials he had snubbed earlier. He remained seated as the Koreans marched, while others around him stood. Pence went to another dinner with US athletes, according to South Korea’s presidential office.

Moon will formally meet the North Korean delegation on Saturday and Kim Yo-jong may invite him to visit Pyongyang this year, according to a report by CNN.

Their white Ilyushin Il-62 jet – marked in Korean script “Democratic People’s Republic of Korea”, the North’s official name, and its tailfin emblazoned with a North Korean emblem – had earlier touched down at Incheon airport near Seoul.

Kim Yo-jong is a key member of the Kim dynasty, which has ruled the impoverished, isolated nation with an iron fist and pervasive personality cult through three generations.

The last member of the Kim family to set foot in Seoul was Yo-jong’s grandfather Kim Il-sung, the North’s founder, after his forces invaded in 1950 and the capital fell.

Three years later, the conflict ended with a ceasefire rather than a peace treaty, leaving the peninsula divided by the heavily fortified Demilitarised Zone and the two sides technically in a state of war.

The North is subject to multiple rounds of UN security council sanctions over its banned nuclear weapons and ballistic missile programmes, while the democratic South has risen to become the world’s 11th-largest economy.

Moon has pushed the Games as a “peace Olympics” that will open a door for dialogue to alleviate tensions on the peninsula and seek to persuade Pyongyang to give up its atomic ambitions.

The significance of Pence and the North Koreans sitting in the same box was not immediately clear. He had been dispatched from Washington for the Olympics in part, he said, to make sure people did not lose sight of how the US government perceived the North as a misbehaving and dangerous neighbour.

