A special train believed to be carrying Kim Jong Un departed Beijing on Wednesday after a two-day visit by the North Korean leader to the Chinese capital.
China also wants the sanctions relaxed and Xi said it "hopes that the DPRK and the United States will meet each other halfway" according to China's state news agency Xinhua, using the initials of the North's official name.
"In a word, Chairman Kim Jong Un's visit to China is an indication that the second North Korea-U.S. summit is drawing near", Moon said.
He said Beijing remains supportive of efforts to end tensions over US demands for a halt to North Korea's nuclear and missile programs. "But we are using various channels including the embassy in Beijing to communicate with North Korea".
Moon, a liberal who took office in 2017, has shuttled between North Korea and the United States to facilitate high-profile nuclear diplomacy including the Kim-Trump summit in Singapore last June.
Kang added.it appears talks are underway between North Korea and the U.S.to settle on a location for the summit, . adding Seoul will also closely communicate with Washington on the matter.
Tuesday was Kim's birthday but there was no word of any official celebrations.
Beijing is Pyongyang's sole major ally and key provider of trade and aid, their ties forged in the blood of the Korean War.
KCNA reported that Kim on Wednesday visited a pharmaceutical plant belonging to Beijing Tongrentang Co.
Asked if China is seeking to use Kim's visit as leverage in trade negotiations with the USA, he added, "China's diplomacy incorporates rich and diverse contents".
North Korea wants relief from the multiple sets of sanctions imposed on it over its nuclear weapons and ballistic missile programmes, while the United States wants the measures to remain in place until it gives up its arms - something Pyongyang has made no public promise to do.
The schedule and route this time was similar to Kim's first trip to Beijing by train last March.
Xi told Kim that that China supports the U.S.
Kim and Xi agreed to jointly study and co-ordinate "the management of the situation of the Korean peninsula and the denuclearisation negotiations in particular", the North's official KCNA news agency reported.
Beijing stands ready to "play a positive and constructive role in maintaining peace and stability and realising denuclearisation on the peninsula and lasting peace and stability in the region", it cited him as saying.
In the morning, Kim visited Tong Ren Tang, located in an economic-technological development zone in Beijing, which is the largest producer of traditional Chinese medicine.
Recently, China may be doing more of the latter, says James Kim, pointing to ongoing rumours of "de facto loosening of sanctions implementation in China".
North Korea has a well-honed talent for playing the world's major players against one another, leading analysts to believe that Kim at this point may be using that skill for leverage to get what he wants from a second summit with Trump: both striking a deal with the USA and keeping his nuclear weapons.
"I don't think they believe it's impossible under President Trump. and this is one of drivers for Xi Jinping to keep Kim Jong Un close", Glaser said, noting that Xi reached out "very quickly" after Kim started engaging with Moon.