North Korean leader Kim Jong Un is believed to remain in "full control" of the country's military forces, the second highest-ranking U.S. military officer said Wednesday as questions continue to swirl around the issue of Kim's well-being.

Noting a lack of any intelligence to "confirm or deny" media reports that Kim is suffering from a serious health condition, Air Force Gen. John Hyten, also vice chairman of the Joint Chiefs of Staff, said, "I assume that Kim Jong Un is still in full control of the (North) Korean nuclear forces and the (North) Korean military forces."

"I have no reason not to assume that," he added.

(Air Force Gen. John Hyten)
[Getty/Kyodo]

Reports have spread globally of the North Korean leader being in fragile condition after surgery, prompting the United States and Japan to collect relevant information, while South Korea claimed there is no sign that his health has deteriorated.

Speculation has increased regarding the North Korean leader's health as he was absent from public view on last Wednesday's anniversary of the birth of his grandfather and the nation's founder, Kim Il Sung, which is one of the most important holidays in the country.

Kim Jong Un, now in his late 30s, became North Korea's leader following the death of his father, Kim Jong Il, in December 2011. There is no formally anointed successor to him.

(North Korean leader Kim Jong Un)
[KCNA/Kyodo]

Observers say he may have health concerns, with the South Korea-based Daily NK citing a source speculating that a number of factors, including his obesity, prolific smoking and "overwork," could have led Kim to undergo heart surgery recently.

In Washington, CNN reported Monday that the United States was monitoring intelligence on the North Korean leader being in grave danger after surgery, citing a U.S. official with direct knowledge.

It is not the first time that the whereabouts of the North Korean leader have drawn attention. In 2014, he was not seen in public for 40 days before he showed up walking with a cane. He was found to have undergone ankle surgery at that time, according to South Korean intelligence officials.