Why Kim Jong Un is not celebrating 40th birthday because of his mother

South Korea's spy agency National Intelligence Service (NIS) said that the young daughter of North Korean leader Kim Jong Un could be his likely heir. NIS said, for the first time, that it considers Kim Ju Ae, who is reportedly 10 years old, as her father's probable successor, referring to analysis of her public activities and the state protocols provided to her.

Kim Ju Ae was seen for the first time just over a year ago and is called by the North Korean state media as Kim Jong Un's "most beloved" or "respected" child. Photos and footage of her accompanying her father at public events have also been shared by the country's media which points to her increasing political standing.

North Korea's leader Kim Jong Un (C) with his daughter Ju Ae. (AFP)

Earlier reports claimed that she is the Kim Jong Un's second of three children, and that the first child is a son. North Korea, one of the world's most secretive nations, has not confirmed whether Kim Ju Ae has any siblings.