Here are the key figures in the North Korean leadership circle and the role they may play in any transition. North Korea has never announced who would follow leader Kim Jong Un in the event he is incapacitated, and with no details known about his young children, analysts say his sister and loyalists could form a regency until a successor is old enough to take over.
South Korean and Chinese officials have publicly cast doubt on reports that Kim was gravely ill following a cardiovascular procedure, after his absence from a key state anniversary event on April 15 triggered speculation about his health. But the media reports sparked questions about who is in place to take over if Kim, thought to be about 36, a third-generation hereditary leader, fell seriously ill or died. He became leader when his father Kim Jong Il died in 2011 from a heart attack.
Each change at the top in North Korea has raised the prospect of a leadership vacuum or collapse of the Kim dynasty, which has ruled the country since its founding in 1948.
So far, each of the three Kims to rule North Korea has defied expectations, holding on to power with an iron grip. But under Kim Jong Un, North Korea’s arsenal of nuclear weapons and ballistic missiles has grown substantially, raising concerns over who would control them.