Chinese president Xi Jinping holds talks with North Korean leader Kim Jong Un in Dalian on May 7-8 2018. Ju Peng | Xinhua | Getty Images

What China wants

Beijing and Pyongyang ultimately possess the same goals for the Trump-Kim summit: get the White House to relax sanctions on the isolated nation, according to Gregory Kulacki, a China expert at the global security program of research and advocacy group Union of Concerned Scientists (UCS). "China and North Korea have cut their deal already," Kulacki said on a UCS podcast. That deal entails Xi's administration resuming some economic relations with Kim's government if the latter freezes missile and nuclear weapons tests, he explained.

But "in order for China to open the economic door a little bit, there is going to have to be some relaxation of those sanctions, which means there's gonna have to be some concession from the United States," Kulacki continued, adding that such a scenario would constitute a victory for both Pyongyang and Beijing. During a May meeting between Kim and Xi, the Chinese leader re-emphasized support for North Korea to stick to denuclearization while Kim was quoted as telling Xi that Pyongyang won't need to possess nuclear weapons if a "relevant party" drops its "hostile policy and security threats," evidently referring to the U.S. Shortly following that encounter, Trump said Kim was possibly being influenced by Xi. The U.S. president also urged China to maintain a secure border with the pariah state. Trump tweet Ideally, China's outcome for the Tuesday meeting is for "a soft landing" — that is, "a denuclearized North Korea that gradually carries out reform and opens up its society, which will make economic dynamism in the sub-region possible," said Ren Xiao, professor of international studies at Shanghai's Fudan University.

What China doesn't want