Mr. Kim, for his part, had a longer-term goal: a good relationship with the United States that would free the North of its economic dependence on China, said John Delury, an associate professor of Chinese studies at Yonsei University in Seoul, South Korea.

“Kim is trying, like the rest of the region, to move North Korea between China and the United States,” Mr. Delury said. “Like everyone else, he is afraid of China’s rise.”

Though the carefully choreographed state media images from Mr. Xi’s visit gave the impression of friendship, its brevity suggested that all was not so smooth, or at least that the two had not had much to talk about, Mr. Delury said.

“It took 14 years for China’s leader to take the two-hour flight to the capital of its closest ally,” he noted. “North Korea has long schemed to survive as an independent entity rather than be China’s sidekick.”