North Korean leader Kim Jong Un did not undergo surgery or any other medical procedure, a South Korean official said Sunday, amid speculation about his health that continues to linger even after he reappeared publicly in recent days.

South Korea responded by firing two shots towards North Korea. No injuries were reported.

North Korea's state media said leader Kim Jong Un attended the completion of a fertilizer plant in a region north of the capital, Pyongyang.

What do we really know about the man who leads North Korea?

Gathering intelligence on perhaps the world’s most secretive, suspicious and difficult-to-read country is incredibly difficult.

There is only one reason that Kim’s heart problems get international attention, Matthew Fisher says. "It is, of course, because North Korea has nuclear weapons."

The minister said he would not reveal what specific intelligence led to that conclusion, but stressed that it had undergone a complex analysis.

A train likely belonging to North Korean leader Kim Jong Un has been parked at his compound on the country’s east coast since last week, satellite imagery showed, amid speculation about his health that has been caused, in part, by a long period out of the public eye.

The trip by the Chinese doctors and officials comes amid conflicting reports about the health of the North Korean leader.

Reports have said Kim is gravely ill after undergoing a cardiovascular procedure.