A frequent visitor to the North says Kim Jong-chol, who is rarely spotted in public, is rumored to be in charge of Kim Jong-un's security. There are claims that he led the operation to arrest Ri Yong-ha and Jang Su-gil, two close confidants of executed eminence grise Jang Song-taek, in December last year.

North Korea is more than ever a Kim family business, with leader Kim Jong-un's older brother Jong-chol playing a key role in ensuring the regime's longevity while his younger sister Yo-jong manages its coffers.

Kim Jong-chol was also apparently the leader of a social club of children of influential North Korean officials, and there is speculation that Jong-chol played a key role in bringing about recent negotiations with Japanese government officials to mend ties amid growing international isolation. But others still believe Jong-chol does not involve himself with politics.

Kim Yo-jong is reportedly in charge of an agency known as Room 38 under the Workers Party which manages the regime's coffers and businesses that earn foreign currency.

The agency used to be overseen by Jang's widow, Kim Kyong-hui, who is also Kim Jong-un's aunt, but Yo-jong gained control after Jang was executed.

One bureau in the agency exports herbal medicine, rare plants and high-quality lumber, while another oversees a glitzy new department store in Pyongyang as well as 124 other department stores across North Korea. The agency trades with Chinese, Southeast Asian and European companies to secure goods to be sold in these department stores.

Due to Kim Yo-jong's influential position, business is booming, and modern coffee shops in these stores are apparently packed with customers. Yet another of the agency's bureaus handles exports of minerals and oil imports.

North Korea experts say Kim Jong-un, who used to depend heavily on his uncle and aunt, feels he is safer entrusting his siblings with influential jobs. His half sister Sol-song also apparently holds a key post.

Kim Sol-song is the eldest daughter of former leader Kim Jong-il's second wife, Kim Yong-suk, and majored in economics and politics at Kim Il-sung University. She was close to her father and reportedly oversaw his security detail and itinerary in the late 1990s. She has served in the Politburo as well as other key posts including the propaganda department.

Ken Gause of CNA Corporation said recently that Sol-song has taken charge of the Workers Party secretariat, which would put her at the apex of the organization that controls information flow.

Only Kim's older half-brother Kim Jong-nam was sidelined in the power struggle early on and lives in lavish exile.