Mr. Xi was expected to wait to go to the North Korean capital until after Mr. Trump’s summit with Mr. Kim. But under that schedule, Mr. Xi would have not seen Mr. Kim again until the end of June or July.
It is without modern precedent for a leader to come to China on back-to-back visits as Mr. Kim has done, Mr. Cheng said.
“This second meeting demonstrated that North Korea wanted China to play a larger role in the denuclearization process,” said Mr. Cheng, a professor at Renmin University. “When Kim enters the meeting with Trump, he will feel more confident, simply his positions on a variety of issues were consulted and sanctioned by the Chinese leader.”
But some Chinese analysts said the warmth between the two leaders on display in Dalian — they sat for a while in wicker arm chairs on a bucolic outdoor terrace — should not be overstated. Mr. Kim retains a streak of independence, they said.
“North Korea was never a vassal state,” said Shi Yinhong, also a professor at Renmin University. It is even less of one now that the United States has agreed to deal with Mr. Kim, he said.
Like Mr. Kim’s visit to Beijing in March, his visit to Dalian was kept under wraps. But early Tuesday afternoon, the Japanese news service Kyodo reported that a plane from the North Korean carrier Air Koryo was at Dalian’s airport. Security at the airport was tight Tuesday afternoon, with flights canceled between 1:30 p.m. and 4 p.m.
Chinese officials will be heading to Tokyo for meetings on Wednesday with South Korean and Japanese counterparts as part of the recent burst of diplomacy over North Korea. Japan, the host of the talks, has been pushing the United States to continue a tough line against Pyongyang.