Amid mounting rumors on North Korean leader Kim Jong-un's health, U.S. President Donald Trump said on Monday that he knows how Kim is doing, but refused to elaborate on details.

Trump said during a press conference at the White House that he does have a "very good idea," but he can't talk about it now.

Trump added that he hopes Kim is fine, repeating that he has a good relationship with the North Korean leader. 

Trump also said that people will probably be hearing about Kim's condition in the not too distant future. 

Last week, Trump said that he believed the report by CNN on Kim's health was incorrect. CNN reported that Washington was looking into intelligence that Kim was in serious danger after surgery.

Kim has not been seen by the public since April 11 when he presided over a politburo meeting of the ruling Workers' Party.