(CNN) There are few notable personalities on the northern side of the Korean peninsula's demilitarized zone. But one of them, Kim Yong Chol, has taken an outsized role in the ongoing rapprochement with both South Korea and the US.
Kim Yong Chol, the vice-chairman of the Party Central Committee, represented Kim Jong Un at key events this year, and is the young leader's top official in charge of relations between North and South Korea.
He's accompanied Kim to Singapore for the historic summit with US President Donald Trump and had previously traveled to New York in May to meet with US Secretary of State Mike Pompeo.
He later went to Washington DC to hand deliver to Trump a letter from Kim Jong Un, an event that helped put the summit back on track after Trump abruptly called it off.
"He is probably one of the most up-to-date North Korean officials about what North Korea's requirements are for the summit," said Catherine Dill, a senior research associate at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey in Calilfornia.
His trip to the US made him the most senior North Korean official to visit the country since 2000, when Vice Marshal Jo Myong Rok traveled to Washington to meet with then-President Bill Clinton in the Oval Office. Madeleine Albright, who was Secretary of State at the time, traveled to North Korea later that month.
Kim Yong Chol is a former head of North Korea's Reconnaissance Bureau, an espionage and special operations organization. He is believed to have been involved in a torpedo attack that sank the South Korean warship Cheonan in 2010, killing 46 South Korean sailors.
His inclusion as part of the delegation from the North that attended the Pyeongchang Olympics in February raised eyebrows given his suspected role in the Cheonan's sinking.
Together with Kim Jong Un's sister Kim Yo Jong, Kim Yong Chol has been regularly photographed by the North Korean leader's side. He attended two meetings between Kim Jong Un and South Korean President Moon Jae-in at the demilitarized zone.