(CNN) President Donald Trump said Tuesday he doesn't know whether North Korean despot Kim Jong Un is ill but nevertheless wished him luck in his potential ailments.

"I can only say this, I wish him well," Trump said when questioned about Kim's condition. "Good luck."

CNN's Jim Sciutto reported Monday the US is monitoring intelligence that suggests North Korea's leader is in grave danger after undergoing a previous surgery, according to a US official with direct knowledge.

A second source familiar with the intelligence told CNN that the US has been closely monitoring reports on Kim's health.

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.

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