AMID NUCLEAR THREATS, '20/20' REPORTS ON NORTH KOREAN LEADER, KIM JONG-UN, AND HIS FRACTURED FAMILY'S 70-YEAR DYNASTIC RULE

Report Features Interviews With Those Who Knew Kim Jong-un and His Assassinated Half-Brother, Kim Jong-nam

'20/20' Airs on the West Coast, Tuesday, Jan. 30 (10:00-11:00 p.m. PST), on ABC

As North Korea and the United States escalate dangerous rhetoric and nuclear threats, experts and citizens are on edge trying to anticipate what may happen next. At the center of it all is supreme leader Kim Jong-un and his fractured family. Now, nearly one year after his half-brother, Kim Jong-nam, was assassinated in a Malaysian airport, "20/20" documents the 70-year rule of North Korea's first family and the cracks within the dynasty. Correspondent Bob Woodruff reports on the brothers' upbringing and explores their contrasting world views, which may have fueled Kim Jong-un's desire to eliminate all of the regime's enemies - even family. "20/20" airs only on the West Coast on Tuesday, Jan. 30 (10:00-11:00 p.m. PST), on ABC. (Rebroadcast. OAD: 1/12/18)

The hour includes interviews with Japanese journalist Yoji Gomi, who was close with Kim Jong-nam and received emails in which he criticized his half-brother's leadership; former NBA star Dennis Rodman, who has made multiple trips to North Korea since 2013 and spent time with Kim Jong-un; Lee Young-guk, the former bodyguard of Kim Jong-un's father; Raquel Carvalho, a South China Morning Post journalist, who had profiled Kim Jong-nam; Anna Fifield, Tokyo bureau chief for the Washington Post; and Dr. Lee Cook-jong, who treated a North Korean soldier who fled to South Korea in November by running across the border despite sustaining multiple gunshot wounds in the process.

After fleeing North Korea, Kim Jong-nam relocated to Macau. There he lived a western lifestyle and became a known critic of Kim Jong-un's leadership. He even sent an email to journalist Yoji Gomi, which he then published, saying "The Kim Jong-un regime will not last long. Without reforms, North Korea will collapse; and when such changes take place, the regime will collapse." Kim Jong-un may not have taken this criticism from his half-brother well: In February 2017, the world was shocked when Kim Jong-nam was assassinated in Kuala Lumpur International Airport in Malaysia. Security camera footage shows two women smearing something on his face and then leaving the scene. It was determined that he was attacked with VX - a highly lethal nerve agent - and it is speculated that Kim Jong-un was the mastermind behind the assassination.

"20/20" is anchored by Elizabeth Vargas and David Muir. David Sloan is senior executive producer.