Trump tweeted that Kim Jong-un is healthy, although there have been no rumors about the North's leader's health recently.

"Kim Jong-un is very healthy. Never underestimate him," US President Donald Trump tweeted today, but did not elaborate.

It is not clear what prompted Trump to suddenly post this message or if he had any specific information on the North's leader's health.

Jamie Ross, a reporter for the Daily Beast, said that the fact that Trump today posted information complimenting Kim Jong-un's health was a surprise, as rumors of the North's leader's condition had subsided since a few months ago.

Kim Jong-un in April did not appear in public for 20 consecutive days, did not even attend the anniversary activities to celebrate the birthday of late leader Kim Nhat Thanh on April 15, sparking many speculations about health.

However, Kim made a comeback at a public event on May 1, smashing rumors about her health condition.

Trump met Kim Jong-un three times during his first term, becoming the first US President to meet a North Korean leader.

According to Woodward, Trump said Kim Jong-un told him everything.