For his part, Kim could be trying to improve ties with Xi - which have been frosty, to put it mildly - in case his outreach to Trump falls flat, analysts say. It was their second meeting, following Kim's visit to Beijing in March.
Regional powers and the United States are seeking to prevent North Korea from obtaining nuclear weapons.
The meeting held in Dalian is the second one between the two leaders.
Trump announced the planned telephone call in a post on Twitter, just days after a USA delegation returned from discussions in Beijing last week with no agreement on a long list of US demands, and ahead of more negotiations next week.
While the historic peace talks summit between North and South Korea at the end of April drew media attention, an activist and pastor has warned that without a focus on human rights, the developments are not an answered prayer for North Korean Christians.
Donald Trump is also due to speak to President Xi today via telephone in a conversation which will include North Korea.
In a cordial and friendly atmosphere, the top leaders of the two parties and the two countries had an all-round and in-depth exchange of views on China-DPRK relations and major issues of common concern.More news: 23 killed as coal mines collapse in Pak
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By not asking the U.S. to reduce or remove its military presence in South Korea during negotiations, North Korea has failed to advance Chinese interests in the talks.
Chinese state media showed pictures of Kim smiling in an outdoors meeting with Xi, and the two leaders strolling along a waterfront. In addition, 65 percent of South Koreans trust Kim Jong-un on his pledge to denuclearize, and Moon Jae-in's approval ratings have shot up to 86 percent.
While China and North Korea have always been allies, their diplomatic relationship grew rocky following Kim's rise to power in 2011.
The North Korean leader's greatest test may still be to come, however, when he sits down for face-to-face talks with Trump that are expected to take place by late May or early June.
There are no regular commercial flights between Dalian and North Korea and the airport was closed to other aircraft while the plane departed, NHK reported.
Trump said Pompeo, who also visited the North several weeks ago, had meetings scheduled with Kim's representatives.
It was not known how long the Xi-Kim meeting had been planned or why Dalian was chosen.
Posts about unusual traffic jams and security in Dalian popped up on Chinese social media.