North Korean leader Kim Jong Un's life still largely remains a mystery, despite the passage of more than six years since he inherited power following the death of his father in late 2011.

But Kim, who is in his 30s, is increasingly undergoing an image transformation since being seen smiling broadly with South Korean President Moon Jae In and Chinese President Xi Jinping during talks with each of them twice this year.

Before North Korea's diplomatic overtures began, under his leadership, it conducted a fast-paced string of nuclear and ballistic missile tests.

[KCNA/Kyodo]

When Kim was exchanging personal insults and threats of war with U.S. President Donald Trump last year, the North Korean leader warned that he will "definitely tame the mentally deranged U.S. dotard with fire."

During his official duties, Kim, the youngest of Kim Jong Il's three sons, has often been seen with a cigarette dangling from his fingers.

He is an avid basketball fan, famously striking up a friendship with flamboyant former National Basketball Association star Dennis Rodman, who has visited him in Pyongyang multiple times.

Kim, born on Jan. 8, 1983 or 1984, attended an international school in Switzerland and studied at Kim Il Sung Military University, an elite educational institution in Pyongyang named after his grandfather, North Korea's founder.

His mother is Ko Yong Hui, a Korean-Japanese born in Osaka. Ko, Kim Jong Il's third wife, is believed to have died in 2004.

With his wife, Ri Sol Ju, a former singer and cheerleader, according to South Korea's spy agency, Kim is believed to have fathered three children, including a daughter who was held by Rodman in 2013 when she was a baby.

Kim showed a ruthless side when he ordered the execution of his once-powerful uncle Jang Song Thaek for treason in 2013. His estranged half-brother Kim Jong Nam was in 2017 assassinated with the lethal nerve agent VX at Kuala Lumpur International Airport. The North Korean regime is widely suspected of being behind the audacious attack.

But the April 27 inter-Korean summit, which was broadcast live, allowed the South Korean public to see a talkative and jovial Kim who showed a deferential manner toward Moon, leading some to feel more positively about him.