United Nations Secretary-General Antonio Guterres said on March 29 he was extremely encouraged by Kim's visit to China and praised the country as "a very important contributor to a solution in this region".

Two days after the Sentosa summit, during a meeting with Xi, US Secretary of State Mike Pompeo conveyed Trump's appreciation of the Chinese president's important advice and help over the Korean Peninsula issue. Pompeo said the US was willing to work with China to promote the realization of denuclearization and lasting peace on the peninsula.

When meeting with DPRK Foreign Minister Ri Yong-ho in Beijing on Dec 7, State Councilor and Foreign Minister Wang Yi called on Pyongyang and Washington to resume their dialogue and resolve each other's concerns "in a balanced way", adding that China supports both Koreas in advancing reconciliation and cooperation.

Aiming to foster a peaceful environment on the peninsula, China put forward a series of solutions including a dual-track approach" and a "suspension-for-suspension" proposal.

The dual-track approach aims to promote parallel progress in denuclearization of the peninsula and the establishment of a mechanism for peace in a synchronized and reciprocal manner, ultimately achieving both goals together. The latter proposal, which calls for the suspension of nuclear and missile activities by the DPRK and the suspension of large-scale military exercises by the US and ROK, seeks to bring the two Koreas back to the negotiating table.

During a phone call with Moon on April 29, Russian President Vladimir Putin stressed that the importance of continuing the efforts of all parties involved toward a political and diplomatic settlement of the Korean Peninsula issue should follow a road map proposed by Russia and China.

While Pyongyang and Seoul have been striving to form a closer relationship, DPRK-US relations have witnessed on-again, off-again twists since the Sentosa summit, casting a shadow on the prospects for peace on the peninsula this year.

Lee, from the Asiatic Research Institute of Korea University, said, "Unless the DPRK and the United States normalize bilateral relations, inter-Korean relations cannot be developed over the long run." She indicated that distrust between Pyongyang and Washington is undermining the hard-won stability in the region and raising concerns that progress may be halted.

On Dec 10, the US Department of the Treasury announced new sanctions against three senior DPRK officials for serious human rights abuses and censorship, incurring Pyongyang's wrath. The DPRK said Washington was "bent on returning DPRK-US relations to the state they were in last year (2017)".

Negotiations after the Kim-Trump summit have also stalled due to differences on a series of key issues including the scale of denuclearization, US sanctions and whether to issue a declaration that war between the Koreas had ended.

At a news conference on Dec 18, US State Department deputy spokesman Robert Palladino reiterated that Washington would maintain sanctions and pressure against the DPRK until the "final, fully verified denuclearization of the Korean Peninsula" had been achieved.

In response, the DPRK's Korean Central News Agency said Pyongyang would not give up its nuclear weapons until the US stopped making regional nuclear threats, citing the US troops stationed in the ROK, and the so-called nuclear umbrella that protects the ROK and Japan.

Trump said a second meeting with Kim may take place this month or next, but there has been no confirmation of this from Pyongyang.

Fan, from the Chinese Academy of Social Sciences, said: "Both Trump and Kim want a second summit ... There is always a danger that either side may feel frustrated at the lack of progress and could try to create leverage by building up tension."

Lee said, "In 2019, the key point will be a second DPRK-US summit. If Kim and Trump reach a visible agreement and Kim visits Seoul early in the year, it would become a game changer."