"Even if the US and South Korea try to weaken China's impact in the negotiation process, Xi and Kim's recent two meetings have proved that China and its support are indispensable", said Yue Li, senior fellow at the Pangoal Institution, a Beijing-based think tank.
"It would be a great mistake for Kim Jong Un to think he could play Donald Trump", Pence said according to excerpts of an interview made available by Fox.
Scott Snyder, director of the Program on U.S. -Korea Policy at the Council of Foreign Relations, said there's a risk that "the ceremony and the historic nature of the meeting be allowed to overshadow the deliverables". It was Moon's government that delivered the initial invitation from Kim for a meeting, and South Korea has been pushing the US toward a peaceful resolution to the nuclear crisis.
On May 12, North Korean state media said the dismantlement process will involve "collapsing all of its tunnels with explosions, blocking its entrances, and removing all observation facilities, research buildings and security posts".
North Korea is a party to the Paris Agreement, the 2015 pact that Trump plans to withdraw the United States from despite an uproar from allies around the world. "Beijing has even less influence over USA policy and President Trump".
The Moon-Trump meeting should be an occasion for the two leaders to reaffirm the principle and urge the North to come to the negotiation table with the genuine intention to denuclearise, which would reward it with security and prosperity. That is typical North Korean brinkmanship.
Since that threat, Trump and others in the White House have denied they are demanding a so-called "Libya model" for disarmament, while still insisting North Korea must give up its nuclear weapons for which it would be richly rewarded.
North Korea - whose carbon emissions rank in the bottom half of nations worldwide - put forward a hefty commitment to cut its greenhouse gases 37.4 percent compared with 1990 levels.
Supporters stress that sometimes Trump's ambitious efforts do pay off, as with the massive tax cut bill he signed into law late past year.
On Monday, Pence said during his Fox News interview that under Trump's leadership, the USA "is not going to tolerate the regime in North Korea possessing nuclear weapons and ballistic missiles that threaten the United States and our allies".
Trump has reportedly been focusing on the pageantry of the summit rather than immersing himself in detailed briefings on the complex issue of North Korea's nuclear programme. Perhaps he even had dreams of making Jared Kushner viceroy of North Korea, while Ivanka started up a new clothing factory with a fresh source of cut-rate labor. The coin also describes Kim Jong Un as "Supreme Leader".
But he warned that the fate of Libya is "what will take place if we don't make a deal".
Earlier this month, with only weeks until the historic summit, North Korea flipped on the US and South Korea, blasting them both with a series of complaints that seemed like a tantrum.
The North claimed the exercises involved USA strategic nuclear assets - including nuclear-capable B-52 bombers - and violated the spirit of detente on the peninsula.
Jane Nakano, a senior fellow at the Center for Strategic and International Studies, said the Trump administration could contribute to that.