Kim Yo Jong: North Korean Leader's Increasingly Powerful Sister

North Korean leader Kim Jong Un's sister warned at the weekend that a Korean liaison office would soon be seen "completely collapsed". On Tuesday, Pyongyang reduced it to rubble.

Kim Yo Jong is one of her brother's most trusted advisers and among the most powerful women in the isolated regime, but her public profile is mounting rapidly and she has been mooted as a potential successor.

The first statement issued in her name came only in March this year, but in recent days and weeks, she has been at the forefront of Pyongyang's denunciations of defectors in the South sending leaflets across the border.

Officially she is only an alternate member of the Political Bureau of the Central Committee, but in a weekend statement carried by the official KCNA news agency, she referred to "my power authorised by the Supreme Leader, our Party and the state".

Born in 1988, according to the Unification ministry, Yo Jong is one of three children born to Kim's predecessor Kim Jong Il and his third known partner, former dancer Ko Yong Hui.

She was educated in Switzerland alongside her brother and rose rapidly up the ranks once he inherited power after their father's death in 2011.

Her existence was barely known to the wider world until his funeral, when she was seen standing right behind Kim Jong Un on state television, looking tearful and ashen-faced.

But more recently she has seemed to be constantly at her brother's side.

Yo Jong has "been very faithful in promoting him as the supreme leader, burnishing his domestic and international image, and helping him practically as his de facto chief of staff," said Katharine Moon, a politics professor at Wellesley College in the United States.

On their 60-hour train journey to Hanoi for his summit with Trump -- which collapsed without a nuclear deal -- Yo Jong was seen bringing him an ashtray when he stepped off for a cigarette break.

There was "no doubt" that Kim has an exceptionally close relationship with his sister, said Yang Moo-jin, of the University of North Korean Studies in Seoul.

"Jong Un and Yo Jong spent much of their lonely childhood overseas together -- I think this is when they developed something that is similar to comradeship, on top of sibling love," he told AFP.

The North has never had a woman leader but speculation swirled over Yo Jong as a potential successor in the event of the death of her brother, after he was absent from public view for weeks earlier this year.

Leadership has always been a family affair in the North, and she is now one of the most prominent members of the "Paektu bloodline" -- a Northern term for Kim Il Sung and his descendants, who have led the nuclear-armed country since its foundation.

And analysts say that her portrayal in state media as the voice of Pyongyang's anger over the activists -- and now a role in a highly visible action -- could be intended to bolster her credibility with the North Korean military and other hawks.

Until recently, Yo Jong has been more associated with the North's diplomatic efforts.

An inscrutable smile played on her lips when she rode down an escalator at Incheon airport as her brother Kim Jong Un's envoy to the 2018 Winter Olympics, becoming the first member of the North's ruling dynasty to set foot in the South since the Korean War.

Every detail of her visit was closely watched, from the clothes she wore to the bag she was carrying and even her handwriting.

When she had a brief meeting with Seoul officials on arrival, the delegation's titular leader Kim Yong Nam -- at the time Pyongyang's ceremonial head of state and a man in his 90s -- offered her the seat of honour.

The Games ushered in a rapid diplomatic rapprochement on the peninsula and she attended a series of summits as aide to her brother, sometimes straying into shot as he walked with US President Donald Trump or the South's Moon Jae-in.

But in keeping with the secrecy shrouding North Korea's leaders, it is not known whether she is married.