Promotion of Kim Jong Un's sister Kim Yo Jong as North Korea's de facto second-in-command has once again put the health of the isolated nation's leader in the spotlight. On Saturday, an expert claimed that Kim Jong Un is "becoming weak" and the recent political changes only proved that.

"Kim Jong-un has never been a healthy man and I can't imagine he's allowed this to happen naturally. ... If he is still alive then he is becoming weak," Roy Calley, a UK-based expert in North Korean affairs, told Express.co.uk. Calley noted that even though North Korea was a male-dominated society, Kim Yo Jong's promotion as the country's de facto second-in-command meant that she was the "natural successor."

Kim Jong Un Not Well?

North Korean leader Kim Jong Un attends a grand military parade celebrating the 70th founding anniversary of the North Korean Army
North Korean leader Kim Jong Un attends a grand military parade celebrating the 70th founding anniversary of the North Korean Army Reuters

"I think this is quite significant as it's clear she is now emerging as the natural successor. North Korea is very much a male-dominated society, so it's inconceivable that he would effectively hand over certain aspects of his leadership," Calley said. "I think there may be a change of leadership in the near future."

However, this was not the first time that speculations over Kim Jong Un's health were rife. Earlier this year, rumor mills were abuzz that North Korea's supreme leader was gravely ill after he missed several public events in April. Some reports even claimed that he was dead. However, he put the rumors to end by making an appearance at the opening of a fertilizer plant in Pyongyang in May.

Despite his appearance, Kim Jong Un's health has been a topic of discussion in the media. Daily NK, a website run by North Korea's defectors, reported the North Korean leader's health deteriorated due to heavy smoking, obesity and overwork. The report also stated that he underwent a cardiovascular procedure during his three-week disappearance.

"My understanding is that he had been struggling (with cardiovascular problems) since last August but it worsened after repeated visits to Mount Paektu," a source told Daily NK, referring to North Korea's sacred mountain.

In June, it was reported that Kim Jong Un was missing in action again triggering concerns over his health. However, Russia's ambassador to Pyongyang Alexander Matsegora said that the reclusive country's leader could be focusing on "rethinking" of the failed outcome of inter-Korean relations.