"I, for one, am glad to see he is back, and well!" Trump tweeted, following Kim's first public appearance in nearly three weeks after intense speculation that he was seriously ill or possibly dead.
North Korean state television showed Kim walking, smiling broadly and smoking a cigarette at what the North said was the opening of a fertilizer factory on Friday in Sunchon, north of Pyongyang.
Rumors about Kim's health have been swirling since his conspicuous no-show at April 15 celebrations for the birthday of his grandfather, the North's founder -- the most important day in the country's political calendar.
His absence triggered a series of fevered rumors and unconfirmed reports over his condition.
Kim's disappearance from public view came as Pyongyang's talks with Washington over the North's nuclear arsenal are at a standstill, despite three meetings between Kim and Trump.
If Kim had been incapacitated or dead, it would have increased uncertainty over the process.
Trump had downplayed reports of Kim's poor health and possible demise.
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