US President Donald Trump hinted on Monday that he knows what is happening with North Korean leader Kim Jong Un, but would not provide details. "I can't tell you exactly. Yes, I do have a very good idea but I can't talk about it, now," Trump told reporters at the White House when asked about Kim. "I just wish him well...I do know how he's doing, relatively speaking. You probably will be hearing in the not too distant future," he added. Speculation has mounted in recent days over the whereabouts of Kim, who last appeared in North Korean state media on April 11 but missed the celebration of his grandfather's birthday on April 15. Last week it was reported that Kim is in grave danger after undergoing heart surgery. The report was denied by a South Korean official. Subsequent reports claimed the North Korean leader is in a vegetative state. On Sunday, a South Korean official told CNN that Kim is "alive and well" and has been staying in the Wonsan area of North Korea since April 13.