Kim recently missed the celebration of his grandfather's birthday on April 15, which raised speculation about his well-being. He had been seen four days before that at a government meeting.
Another US official told CNN Monday that the concerns about Kim's health are credible but the severity is hard to assess. Daily NK, an online newspaper based in South Korea that focuses on North Korea, reports that Kim reportedly received a cardiovascular system procedure on April 12.
Kim received the cardiovascular system procedure because of "excessive smoking, obesity, and overwork," according to the news site, and is now receiving treatment in a villa in Hyangsan County following his procedure.