Following their historic meeting in Singapore last June, negotiations have somewhat stalled, as the White House demands that North Korea dismantle its nuclear program first, before the United States would lift any of its punitive measures on the country.
North Korea also needs to stay close to its Korea War ally if diplomacy fails.
Kim's grandfather Kim Il Sung was also adept at playing off Communist rivals Beijing and Moscow against each other during the Cold War to extract concessions from both.
Like his father - Kim Jong-il, who ruled North Korea from 1994 to 2011, Kim's strength has always been his "vagueness" about what he'll do next, and an ability to "keep everybody guessing until they do it", said James Kim.
Experts think Kim's China trip was meant to discuss strategies with his closest ally ahead of a possible summit with Trump, adding that it also appears aimed at strengthening the North's negotiating leverage by demonstrating its strong ties with Beijing.
Pyongyang could be using the visit to show the U.S. that it has an "alternative power to gravitate towards", according to Tai Wei Lim, a research fellow at the National University of Singapore. Satellite images and intelligence reports show North Korea "has continued nuclear and missile production", even expanding their operations, upgrading equipment such as reentry vehicles and mobile missile launchers, Klingner added. Other times, he has praised China's efforts as interlocutor.
"The Korean peninsula situation has been easing since a year ago, and China's important role in this process is obvious to all ... the DPRK side highly and sincerely appreciates the Chinese efforts", Kim said.
In a New Year's address, Kim pledged his commitment to complete denuclearization in a message to Washington and expressed his desire to meet again with Trump - a sentiment immediately reciprocated by the US president over Twitter.
He did not elaborate what such an alternative path could be.
"We will not loosen our guard until the promise to denuclearize the Peninsula is kept, and peace is fully institutionalized", added Moon.
Moon's overture, however, has invited criticism from conservatives in South Korea and the United States that he's making too many concessions and helping the North weaken USA -led sanctions.
He harkened back to Beijing's efforts in the now defunct six-party talks. "If China must be described as a factor in this whole process, then China is, and will always be, a positive factor".
North Korean state news agency KCNA has said Mr Kim and Mr Xi held "in-depth, frank discussions" on the Korean peninsula and nuclear issues during his stay in Beijing, his fourth since March 2018.
"China stands ready to work with the DPRK and relevant parties to play a positive and constructive role in maintaining peace and stability and realizing denuclearization on the peninsula and lasting peace and stability in the region".
The high-level meeting was supposed to happen in early November in NY but was postponed on the request of Pyongyang.
South Korea's Yonhap News Agency says it will take 14 hours for the train to reach the city of Dandong at the North Korean border.
"The second North Korea-United States summit - to take place soon - and a reciprocal visit to Seoul by Chairman Kim Jong Un of North Korea will be.turning points that will firmly solidify peace on the Korean Peninsula", said Mr Moon in his speech. CNN reported Tuesday that Bangkok, Hanoi and Hawaii have been visited by White House scouting teams, citing a source familiar with the planning process. It comes after USA and North Korean officials are thought to have met in Vietnam to discuss the site of the summit.