North and South Korean officials sit side by side at the opening ceremony of Winter Olympics

US vice president Mike Pence, who is in Pyeongchang to cheer on American athletes, sat a row ahead of Ms Kim and the North’s nominal head of state, Kim Yong Nam, as they watched the games begin - officials from two nations that many worry are on the brink of nuclear conflict.

The opening ceremony took place before a world watching the Games not only for their athletic significance and global spectacle, but for clues about what the political future of the peninsula could hold. A delegation from North Korea, dressed in identical garb, watched from an upper deck of the stadium.

Then began the Olympic tradition that takes place at every Games - the march of athletes from the world’s many nations, which took place during freezing temperatures and biting winds.

Performances displayed the sweep of Korean history and culture. Members of a delegation from North Korea, part of an extraordinary Olympics partnership between the two Korean rivals, watched from high in the stadium a performance called “The Land of Peace”, and also watched past South Korean athletes parade a large southern flag.

After a chaotic year of nuclear war threats and missile tests from the North, it was a striking visual moment.

There was a palpable excitement in this isolated, rugged mountain town, as one of the poorest, coldest and most disgruntled parts of an otherwise prosperous South Korea kicked off two weeks of winter sports, Olympic spectacle and, perhaps, reconciliation between the North and South.

The rival Koreas, flirting with war just weeks ago, are suddenly making overtures toward the no-longer-quite-so-absurd notion of cooperation.

Mr Moon said at a reception ahead of the ceremony: “Athletes from the two Koreas will work together for victory, and that will resonate with and be remembered in the hearts of people around the world as a sign of peace.”

The North has sent nearly 500 people to the Pyeongchang Games including officials, athletes, artists and cheerleaders after the Koreas agreed to a series of conciliatory gestures to mark the event.

More than 2,900 athletes from 92 countries will compete, making it the biggest Winter Olympics to date.

Meanwhile, Mr Pence called on the international community to get tougher on North Korea’s nuclear ambitions and human rights abuses.

Mr Pence warned the world against falling for the glossy image of the two Koreas as they march in the opening ceremony under one flag.

After meetings with Mr Moon and Japanese prime minister Shinzo Abe, Mr Pence said there should be no consideration of using the Games as an opening for substantive talks with the North until its nuclear programme is up for negotiation.

Mr Pence said the US would “demand at the outset of any new dialogue or negotiations that the Kim regime put denuclearisation on the table and take concrete steps with the world community to dismantle, permanently and irreversibly, their nuclear and ballistic missile programmes”.

He added: “Then and only then will the world community consider negotiating and making changes in the sanctions regime that’s placed on them today.”

Mr Pence seeks to counter what he called North Korean “propaganda” around the Winter Olympics, and is eager to put a reality check on the thaw in relations between the Koreas in advance of the Games.

He met North Korean defectors and paid respects at the Cheonan Memorial in Pyeongtaek, which honours the 46 South Korean sailors killed in a 2010 torpedo attack blamed on the North.

Mr Pence warned that the world would see “a charm offensive by North Korea” on Friday, “but today we thought it was important to make sure the truth is told.

“As these people and their lives testify, it (the North) is a regime that imprisons, and tortures, and impoverishes its citizens.”