Looking at what happened between South and North Korea in PyeongChang and Seoul over the weekend, some might have difficulty believing that until a short while ago, the two were seemingly at each other’s throats, ready to be swept into war in a US-North confrontation over the nuclear crisis.

Athletes from the two sides marched together under the Korean Unification Flag at the opening ceremony of the PyeongChang Games. Two members of the unified women’s hockey team -- one from each side -- climbed together up the stairs to relay the torch for igniting the flame in the Olympic Stadium. It was a symbolic scene of the Olympics promoting peace in a divided nation.

Adding to the quickly formed rapprochement mood between the two Koreas were the performances of a North Korean art troupe, cheering squads made up of young women and a taekwondo demonstration team. Indeed, the North Korean visitors have charmed many South Koreans.

The highlight of the reconciliatory atmosphere, of course, was meetings between President Moon Jae-in and a high-powered North Korean government delegation, led by its nominal head of state and the sister of the North Korean leader, Kim Yo-jong.

Kim Yo-jong, who Moon’s aides said was Kim Jong-un’s special envoy, conveyed an invitation from her brother for Moon to visit Pyongyang at an early date. It was hardly a surprise that Moon said he would like to make it happen by creating the necessary conditions.

It seems that the two sides have successfully built momentum for arranging the first inter-Korean summit since Moon’s former boss and mentor Roh Moo-hyun and the North Korean leader’s late father, Kim Jong-il, met in Pyongyang 10 years ago.

But unguarded optimism is the last thing you should have when you deal with North Korea. Look no further than where the two Koreas are -- especially regarding the North’s nuclear and missile ambitions -- after two summits, including the historic 2000 meeting between Kim Dae-jung and Kim Jong-il.

This time, the North’s sudden peace overture may well be part a propaganda tactic aimed at taking advantage of the Moon government’s engagement policy to improve its image and loosen international sanctions against its nuclear and missile provocations.

In fact, the North has already achieved some of its objectives. The North, thanks to the active intervention of the Moon government, was allowed to send a ferry to transport an art troupe, which otherwise would have been banned under the UN-led sanctions.

The Seoul government also persuaded the UN to endorse a temporarily suspension of a travel ban on a blacklisted senior North Korean official.

To the eyes of some, like US Vice President Mike Pence and Japanese Prime Minister Shinzo Abe, all that has happened between the two Koreas should be a cause more for concern than hope.

Pence and Abe warned against the North’s “charm offensive” and “smile diplomacy,” which they believe could send the wrong message to North Korea and cause cracks in the international alliance to check the North.

Pence apparently intentionally shunned sitting together with Kim Yong-nam, the North’s nominal head of state who led the North Korean government delegation, during a reception hosted by Moon. He also has spent more of his time here criticizing the North’s human rights oppression and emphasizing the need to continue maximum pressure rather than preaching about reconciliation and peace.

The message Pence wanted to send was clear: Any progress made in relations with the North is meaningless unless the North abandons nuclear bombs and missiles and improve its rights conditions.

The festivities and hustle and bustle surrounding North Koreans will be over with the closing of the Olympics in two weeks. Then the world will again face the cold reality: How will it force or persuade the North to give up its nuclear and missile programs?

Inter-Korean dialogue and expanded engagement may be necessary, but it won’t be sufficient for achieving the goal. Much will depend on what course of action Kim Jong-un takes after the Olympics. The best will be -- as Moon suggested to his sister -- Kim deciding to talk with the US on a condition Washington could agree to.