BEIJING/SEOUL-- Chinese President Xi Jinping's special envoy on Friday left for North Korea amid strained bilateral ties over Pyongyang's nuclear and missile programs.

The trip by Song Tao, the head of the international department at the Central Committee of the Communist Party, comes after Xi and U.S. President Donald Trump held a summit in Beijing last Thursday.

A Chinese delegation consisting of around five members was found at an airport in Beijing. North Korea's top envoy to Beijing Ji Jae-ryong saw him off.

Details about his itinerary have not been unveiled, but diplomatic sources said that he may make a four-day visit to the North, during which he could meet with North Korean leader Kim Jong-un.

Seoul's unification ministry said that China's special envoys dispatched to the North after the party congresses in 2007 and 2012 met with former North Korean ruler Kim Jong-il and the current leader, respectively.

China's foreign ministry said that the two sides will exchange views on issues of mutual interest at the party and country level, and that Song will report on the outcome of China's party congress.

It is customary for China and North Korea to send a delegation to each other for briefings on the results of important party events.

But Song's trip comes on the heels of Trump's 12-day tour of Asia. Trump has called on China to do more to rein in the wayward regime.

Experts say that the issue of North Korea's nuclear and missile programs is likely to be discussed at a time when Pyongyang has suspended its provocative acts for more than 60 days.

Joseph Yun, the top U.S. nuclear envoy, reportedly said at a recent meeting that if North Korea halts nuclear and missile testing for about 60 days, that would be the signal Washington needs to resume direct dialogue with Pyongyang.

Yun was in South Korea's southern Jeju Island to have talks over North Korea's nuclear issue with his South Korean counterpart Lee Do-hoon.

The U.S. envoy said he hope that Song's trip would help "forward" the goal of its denuclearization.

Lee also added that it could have "a very significant meaning considering the current situation."

Yun said in Seoul on Tuesday that he does not know the reason for North Korea's halting of provocations, but he called on the North to stay that course "for a period of time."

Meanwhile, North Korea's main newspaper said Friday that the country will not put issues directly linked to its core interests and its people's security on the negotiation table.

"The United States should abandon its hostile policy toward North Korea. If Washington does not give it up, we will not budge by an inch from the path to strengthening our nuclear force," said the Rodong Sinmun, the mouthpiece of the ruling Workers' Party of Korea.

Source: Yonhap News Agency