Chung had spoken to Yang Jiechi, China's top diplomat, for three hours prior to meeting Mr Xi, the South Koreans said.
Trump dispensed with decades of USA foreign policy orthodoxy with his decision, particularly given that the North Korean leader made only a vague offer - conveyed via a South Korean delegation that visited him - to discuss giving up his nuclear weapons program.
The goal of the meeting remains denuclearization of the Korean Peninsula, something Kim has agreed to discuss, they said.
"We have a precious chance that must not be lost, not just for this government but also for the nation of the Republic of Korea", Moon Jae In, South Korea's president, said recently.
Some experts are concerned that North Korea could be seeking to delay global action while strengthening its nuclear program.
China's warm welcome to Chung, which contrasts starkly with the lackluster protocol during Moon's own visit in December a year ago, reflects an increasing sense of unease in Beijing over the U.S. The South Korean officials who carried Mr Kim's invitation to Washington will split up to visit the leaders of China and Japan this week to update them on the talks, a South Korean presidential official said on Sunday.
Cheong Seong-chang is an expert on North Korea at the Sejong Institute in South Korea. Carranza said the meeting place will be a crucial factor. Curiously, North Korea's closely-controlled state-run TV news service didn't show any of the recent Winter Olympics.
Trump made the announcement after the head of a South Korean delegation that met Kim last week said the North Korean leader had committed to denuclearization and pledged to refrain from nuclear and missile tests. "It legitimizes, in their view, their dictatorship and legitimizes their nuclear weapons program".
Yet China has long shared the USA objective of eliminating North Korea's nuclear weapons. Secretary of StateRex Tillerson was essentially out of the loop when Trump made his snap decision to agree to a meeting.
Tillerson's remarks that these things take time contrast with Trump's on-the-spot acceptance of Kim's invitation when South Korea's national security adviser informed him about it at the White House last week. That's surely unknown. The hermetic kingdom of North Korea is one of the most closed countries in the world.
".but, again they - they cannot engage in missile testing, they cannot engage in nuclear testing and they can't publicly object to the U".
Kim could face similar problems travelling to the United States, where no North Korean leader has visited, making many observers think a more neutral setting will need to be found.