Kim Yo-Jong and Kim Jong-un
North Korean leader Kim Jong-un is frequently accompanied by his younger sister Kim Yo-jong at public events REUTERS/Damir Sagolj

North Korea's leader Kim Jong-un appointed his younger sister, Kim Yo-jong, to the country's top decision-making body – the Workers Party's Politburo – on Saturday (7 October), as he seeks to tighten his grip on power amid mounting escalation between Pyongyang and Washington.

Few people knew her name before this weekend, but Yo-jong has quietly been making her mark on the Pyongyang regime for years.

Yo-jong, 30, is considered one of her brother's closest aides and the mastermind behind the supreme leader's carefully constructed image as "father of the people".

She and her brother are said to be very close, after spending much of their childhood separated from the rest of their family while they went to school in Berne, Switzerland.

After completing her education, Yo-jong became a junior member of the Workers' Party, working for her father and aunt. She rarely appeared in public until 2010 when she was photographed attending a party conference.

But it was not until Kim Jong-il's death and her brother's anointment as the third leader of the Kim dynasty that she started rising up the political ranks in Pyongyang.

Yo-jong played an important role in Kim Jong-un's succession campaign, according North Korea Leadership Watch, which was founded by US scholar Michael Madden.

Since his anointment, she has regularly been seen with her brother at public events, such as a trip to an equestrian displayin 2012 and other "field guidance visits", and become one of the most visible women in the leader's entourage, alongside his wife Ri Sol-ju.

Madden described her as one of the dictator's "closest confidantes" in an article on the 38 North website in 2014. "Given the patriarchal nature of North Korea's political culture she is not a candidate for succession," he said.

Kim Yo-Jong
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 on 13 April 2017 REUTERS/Damir Sagolj

Her move into politics was officially recognised by North Korean state media in 2014 when she attended the Supreme People's Assembly with Kim, and was referred to as a senior party official.

Later that year she was appointed vice-director of the Workers' Party propaganda and agitation department, which is responsible for presenting Kim Jong-un as a benevolent leader, following in the footsteps of his grandfather Kim Il-sung.

Yo-jong currently works in Kim's executive office, where she manages his public appearances and security arrangements, according to North Korea Leadership Watch.

Her new position on the Politburo indicates that her "portfolio and writ is far more substantive than previously believed", Madden wrote on 38 North. "It is a further consolidation of the Kim family's power," he added.

Sierra Madden, a contributor to North Korea Watch, told IBTimes UK that Yo-jong's appointment to the Politburo proves that "she was already powerful. She has had her brother's ear for a while."

"Her promotion formalizes the reality of the influence she already had," she said.

Yo-jong's quiet rise to power has not escaped the notice of US authorities, who placed her on a blacklist in January for "severe human rights abuses".

Phil Robertson, deputy director of Human Rights Watch's Asia division, told IBTimes UK that Yo-jong's ascendance "signifies what many suspected...that holding dictatorial power and systematically violating human rights is a family affair at the top echelons of North Korean government. As a person who apparently serves closely with dictator Kim Jong-Un, Yo-jong both oversees and benefits from the horrific rights violations being committed every day by the North Korea state."