Transcript for Who is 'Supreme Leader' Kim Jong Un?

In the meantime many say one of the victories of Kim Jong-un is simply standing on the same stage as the preside of the United States. He'll get that chance after taking over in his mid twenties and killing his uncle and believed killing his brother with a nerve agent. Who is the man about to sit across from president trump? Reporter: He is the 34-year-old leader of north Korea. Kim Jong-un. His official birth date has never been confirmed. Known for his dress, right down to his platform shoes, and his pursuit of nuclear weapons. When his father died of a heart attack at 70 from what the north Koreans said W over work. It was his youngest son Kim Jong-un who wouldake over. Just last September he tested what was believed to be a hydrogen bomb. Knn to the north Koreans as the supreme leader the world got its first glimpse of Kim Jong-un at his father's funeral in 2011. He was one of the pallbearers walking alongside with father's casket, crying at hifather's wake. As North Korea's leader he has demonstratede's willing to kill to keep his power. Publicly executing his own uncle. He feared he was planning a coupe. Even his older half-brother, once believed to be the original heir to the Kim dynasty. Surveillance footage show two women smearing a deadly nerve agent on his face here, asking for help in the moments after. He was dead within minutes. It's thought he has killed more than 140 senior officials to keep his grip on power. The north Korean people have struggled with little food and black outs. Th satellite image showing a dark nation when the sun goes down. That brutality reaching Americans, too. 22-year-old American student Otto Warmbier was on a guided tour trip when he S accused of stealing a propaganda poster at his hotel in 2016. Please! I've made the worst mistake of life. Reporter: Sentenced to 15 years hard labor, he served 18 months before being released back to the U.S. In a coma, eventually dying from unexplained injuries. His parents are still demanding aners. Obedience drilled into north Koreans at a young age. They are taught songs praising their leader. Propaganda everywhere. The military parades. The uniform marching. Defectors tell stories of starvation and labor camps. This video a north Korean soldier trying to defect, surviving a hail obullets as he crossed the border. He went to school in Switzerland for a time. He enjoyed western culture -- movies and basketball. He is marriednd believed he has three children. His wife is more of a public figure in North Korea. She is called respected first lady. Just this year Kim Jong-un and his expected olive branch to South Korea. Now he is set talk up to president trump for that face-to-face meeting being watched by the world. The north Korean dictator set to sit down with president trump a short time from now. We're learning more about Kim Jong-un's younger sister. She arrived in Singapore on separate plane for security

This transcript has been automatically generated and may not be 100% accurate.