North Korea has always had China as a diplomatic ally.

Posting a photo of Mr. Kim boarding an Air China Boeing 747 was a surprising display. Photo: AP

Kim Jong-un has not taken such a long flight since he took power in December 2011, and the North Korean leader's flight on a Chinese airline shows that the two Cold War allies still need each other, despite recent tensions.

According to analysts, the North Korean Workers' Party newspapers published a photo of Mr. Kim boarding an Air China Boeing 747, which was a surprising display, because North Korea has always prided itself on its sense of self-reliance.

Professor Koh Yu-hwan, who studies North Korea at Dongguk University in Seoul, commented: “This may be a practical reason, but it is also a symbolic move to show the people that China always has North Korea's support and that Beijing can be there for Pyongyang if the entire denuclearization process between North Korea and the US fails.”

Analysts also believe that Beijing is always concerned about Kim Jong-un's personal safety, as North Korea's aircraft fleet is old. Kim Jong-un's father, the late North Korean leader Kim Jong-il, was known to be afraid of flying and only traveled by train.

In the past, the late North Korean President Kim Il Sung was very adept at creating conflict between two former Cold War communist enemies, Beijing and Moscow, in order to gain concessions from both countries.

“Pyongyang may think that it can now use similar tactics against China and the US to achieve its own interests,” Professor Koh said.

At the same time, Kim Jong-un wants to strengthen relations with powers like China and Russia to protect himself if Pyongyang begins to dismantle its nuclear arsenal, which is considered its “treasured sword,” according to Mr. Koh.

Lu Chao, a North Korea expert at the Liaoning Academy of Social Sciences (China), said: "China is likely to remain vigilant against possible bluffs by South Korea and the US."

This expert warned that if Washington, Seoul and Pyongyang sign a peace treaty to officially end the state of war on the Korean Peninsula without Beijing's participation, "China has the right to cancel it."

Thus, it can be seen that China will closely monitor the developments of the US-North Korea summit, because this is a national security issue of great importance to this country.