It must have been a relief for South Korean President Moon Jae-in to see the 2018 PyeongChang Winter Olympics come to an end. Despite criticisms on him for his soft stance on North Korea and US President Donald Trump's disapproval of his interactions and reaching out to the North, the Games wrapped up without a nuclear weapon being fired.

Sports is a good enabler of politics. There are numerous examples in recent history where sports events were employed to promote bilateral relations. Taking advantage of the Winter Olympics, North Korean leader Kim Jong-un offered an olive branch and demonstrated his willingness to establish contact with South Korea, seeking to portray the international community a peace-loving image of North Korea, which demonstrated his diplomatic skills.

The visit of his younger sister Kim Yo-jong to South Korea during the Winter Olympics drew especial attention. She handed over her brother's letter to Moon in Seoul, inviting the South Korean president to Pyongyang. The move underscored North Korea's efforts to alleviate pressures brought by sanctions by improving inter-Korea ties. 

Whether Moon will pay an idea to North Korea on the invitation of Kim needs to be pondered. But it is obvious that Trump strongly opposes the idea. The US president insists on tough policies toward Pyongyang.

Kim offered an olive branch to South Korea because the sanctions imposed on the North by the international community have worked. North Korea now is short of food, electricity and gasoline, which has severely affected people's livelihood. Kim intended to make use of the Winter Olympics to extricate his country out of the quagmire. But his strategy of public diplomacy was countered by the US. US Vice President Mike Pence invited Fred Warmbier, the father of the late Otto Warmbier, to South Korea for the Winter Olympics opening ceremony. Otto, a University of Virginia student, died after being held captive in North Korea for 17 months.

The US imposed the largest-ever sanctions on Pyongyang when the Olympics were coming to an end, which made Kim's public diplomacy look like a specious victory. 

North Korea could hardly bear further sanctions. The collapse of its economy is a matter of time should sanctions continue. The US holds that all efforts to sanction North Korea would be wasted once inter-Korea tensions ease. It is for this reason that the US slapped the largest-ever sanctions on Pyongyang - a warning to Moon that he shouldn't go too far in improving ties with the North, as well as a warning to Kim that the US will not let the North Korean economy grow if Pyongyang keeps developing nuclear weapons. 

The history of the Korean Peninsula crisis has not seen long-lasting thaws. The Trump administration believes that the North Korean nuclear issue cannot be allowed to drag on. The US policy of "strategic patience" under the administration of Barack Obama is over. It is futile to contain North Korea's nuclear ambition by talks and engagement. Washington believes that only sanctions will work.

So, how would the situation develop?

First comes the question— who will dominate, Trump or Kim? According to my observations, if the US insists on sanctions against North Korea, it would be impossible for Moon to further improve inter-Korea ties since he lacks the strength and courage to act against Washington.  

Besides, his Moonshine Policy, a modified version of former South Korean president Kim Dae-jung's Sunshine Policy and aims at closer engagement with North Korea but with more cautious, has met some domestic opposition. The opposition says that Moon made the 2018 PyeongChang Winter Olympics a Pyongyang Olympics, giving Kim the chance to burnish the image of North Korea.

The second question is what measures would Kim take to deal with the situation. It's reported that high-ranking officials from North Korea said their country was willing to start a dialogue with the US during their visit to South Korea during the Winter Olympics. Responding to this, the US set preconditions for talks saying it is willing to talk to North Korea but only if those talks will lead to an end of the North Korean nuclear program.  

The problem now is that there has been no trust left in Kim. No one believes he would give up nuclear weapons. This is the real challenge.

The author is a senior research fellow of the Charhar Institute.