Moon Jae-in, Kim Yo Jong.

Tim Balk, Tribune News Service

Not much is known about Kim Yo Jong, the younger sister of North Korean dictator Kim Jong Un. Her past is a hazy mystery mostly blinkered by controls the hermit nation keeps on information out of the country.

But as Kim Yo Jong steps into the spotlight, serving as the public face of North Korea’s steps to incinerate its detente with South Korea, two realities have grown increasingly clear. She’s a powerful player. And she talks the talk.

The sister of the supreme leader has unleashed a series of scalding statements in recent days, bashing South Korean President Moon Jae-in as “impudent,” “hideous” and “fake.” She has slammed South Korean efforts to de-escalate tensions with special envoys as “sinister” and “disrespectful.”

The fiery rhetoric was coupled with literal flames on the Peninsula when North Korea demolished a joint liaison office near the border with South Korea on Tuesday, an explosion in Kaesong that echoed around the world as the North airs grievances with its neighbour and the US.

The source of the rising animosity is hard to trace. North Korea has expressed frustration with flyers that waft north over the countries’ airtight border, carrying criticism of Kim Jong Un. But defectors have flown the leaflets for years, and analysts say North Korea may simply be timing its theatrics with the upcoming US presidential election, perhaps also seizing on domestic troubles facing President Donald Trump.

No matter the source, a week’s worth of provocations have shown beyond a doubt that Kim Yo Jong is serving as a de facto deputy for her older brother, and perhaps positioning herself to take the leadership if he were to die. (His health has been a subject of international fascination for months, and the portly leader’s public appearances have proved sparse.)

Victor Cha, a Georgetown University professor and former North Korea adviser to President George W. Bush, said Kim Jong Un views his younger sister as “the only person he can really trust” and is setting her up with her own power base.

“The amazing thing is here you have two 30-something-year-olds who are running a renegade nuclear weapons state,” Cha told the New York Daily News. “And she can be extremely charming, but then we see that she can also be quite ruthless, and have her name associated with blowing up a very important symbol of inter-Korean cooperation.”

Kim Jong Un is believed to be about 36. Kim Yo Jong is thought to be about 32. Kim Jong Un isn’t close to his brother Kim Jong Chol. Another older brother, Kim Jong Nam, was killed in 2017, and North Korea denied widespread accusations that Kim Jong Un ordered his assassination.

But Kim Jong Un does share a bond with Kim Yo Jong. The two both attended school in Switzerland around the same time in the 1990s.

“That’s probably where a lot of their relationship developed,” said Michael Madden, a North Korea watcher and non-resident fellow at the Stimson Center, a think tank.

Madden said Kim Yo Jong was popular at school in North Korea, and that classmates found her “very down to earth and very relatable.” She frequently wore red clothing, he said, and people speak openly about their affection for her. “Kim Jong Un is more of a cypher,” Madden told the Daily News.

As North Korea again turns inimical, a different voice may have surfaced to trade barbs with US leadership. Whatever the status of her brother, Kim Yo Jong has arrived on the international stage.

Sung-Yoon Lee, a North Korea expert at Tufts University’s Fletcher School of Law and Diplomacy, said her rising status amid her brother’s health travails is inextricably linked to the country’s dynastic line.