Video: Kim Jong-un leads celebrations for 70th birthday of his late father Kim Jong-il Kim Jong-un and the military gathered in Pyongyang's Kumsusan Sun Palace to watch a lavish display of military strength in celebration of the late leader on his 70th birthday. Thousands of soldiers lined up in the square to chant and cheer the memory of Kim Jong-il, who died of a heart attack in December last year at the age of 69.