Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, looks on in the garden of the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, looks on in the garden of the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

North Korea's leader Kim Jong Un, U.S. President Donald Trump, Kim Yong Chol, Vice Chairman of the North Korean Workers' Party Committee, and U.S. Secretary of State Mike Pompeo talk while Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee looks on at the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, looks on at the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, looks on at the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, looks on at the Metropole hotel during the second North Korea-U.S. summit in Hanoi, Vietnam February 28, 2019. REUTERS/Leah Millis 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un arrives at the North Korean embassy in Hanoi, Vietnam, February 26, 2019. REUTERS/Jorge Silva 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un and first vice department director of the ruling Workers’ Party’s Central Committee, arrives at the Dong Dang railway station, Vietnam, at the border with China, February 26, 2019. REUTERS/Athit Perawongmetha 

North Korean leader Kim Jong Un's sister Kim Yo Jong attends an official welcome ceremony at Pyongyang Sunan International Airport, in Pyongyang, North Korea, September 18, 2018. Pyeongyang Press Corps/Pool via REUTERS 

Kim Yo Jong shows a document to her brother, North Korea's leader Kim Jong Un as U.S. Secretary of State Mike Pompeo shows a copy of it to President Donald Trump before they sign them at their summit at the Capella Hotel on Sentosa island in Singapore June 12, 2018. REUTERS/Jonathan Ernst 

North Korea's leader Kim Jong Un looks at U.S. President Donald Trump as Kim's sister Kim Yo Jong exchanges document with U.S. Secretary of State Mike Pompeo at their summit at the Capella Hotel on Sentosa island in Singapore June 12, 2018. REUTERS/Jonathan Ernst 

Kim Yo Jong, sister of North Korea's leader Kim Jong Un, visits The Marina Bay Sands hotel in Singapore, June 11, 2018. REUTERS/Edgar Su 

North Korean leader Kim Jong Un applauds with his wife Ri Sol Ju and sister Kim Yo Jong at the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Korea Summit Press Pool/Pool via Reuters 

North Korean leader Kim Jong Un's sister Kim Yo Jong walks at the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Korea Summit Press Pool/Pool via Reuters TPX IMAGES OF THE DAY 

North Korean leader Kim Jong Un is assisted by his sister Kim Yo Jong as he signs documents at the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Korea Summit Press Pool/Pool via Reuters 

South Korean President Moon Jae-in watches as North Korean leader Kim Jong Un prepares to write in a guestbook with his sister Kim Yo Jong during their meeting at the Peace House at the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Korea Summit Press Pool/Pool via Reuters 

North Korean leader Kim Jong Un and his sister Kim Yo Jong attend a meeting with South Korean President Moon Jae-in at the Peace House at the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Korea Summit Press Pool/Pool via Reuters 

North Korean leader Kim Jong Un and his sister Kim Yo Jong attend an opening ceremony of a newly constructed residential complex in Ryomyong street in Pyongyang, North Korea April 13, 2017. REUTERS/Damir Sagolj TPX IMAGES OF THE DAY 

Kim Yo Jong, sister of North Korean leader Kim Jong Un, attends an opening ceremony of a newly constructed residential complex in Ryomyong street in Pyongyang, North Korea April 13, 2017. REUTERS/Damir Sagolj TPX IMAGES OF THE DAY 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - President of South Korea Moon Jae-in, his wife Kim Jung-Sook and Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un during the opening ceremony. REUTERS/Kim Kyung-Hoon 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - IOC President Thomas Bach, President of South Korea Moon Jae-in, his wife Kim Jung-Sook, President of the Presidium of the Supreme People’s Assembly of North Korea Kim Young Nam, Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un greet united Korea team during the opening ceremony. REUTERS/Kim Kyung-Hoon 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - President of South Korea Moon Jae-in, his wife Kim Jung-Sook, resident of the Presidium of the Supreme People’s Assembly of North Korea Kim Young Nam and Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un during the opening ceremony. REUTERS/Kim Kyung-Hoon 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - Kim Yo Jong, sister of North Korean leader Kim Jong Un, South Korean President Moon Jae-in, and IOC President Thomas Bach attend the opening ceremony. REUTERS/Damir Sagolj 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - President of South Korea Moon Jae-in, his wife Kim Jung-Sook and Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un during the opening ceremony. REUTERS/Kim Kyung-Hoon 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - President of South Korea Moon Jae-in, his wife Kim Jung-Sook, resident of the Presidium of the Supreme People’s Assembly of North Korea Kim Young Nam and Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un during the opening ceremony. REUTERS/Kim Kyung-Hoon 

Pyeongchang 2018 Winter Olympics – Opening ceremony – Pyeongchang Olympic Stadium - Pyeongchang, South Korea – February 9, 2018 - President of South Korea Moon Jae-in, his wife Kim Jung-Sook, Kim Yo-Jong, the sister of North Koreas leader Kim Jong-un and German President Frank-Walter Steinmeier during the opening ceremony. REUTERS/Kim Kyung-Hoon