The morning after the opening ceremony, Kim exited a black sedan to enter the Blue House. She ambled down a red carpet with immaculate posture and her head held high, exuding the confidence of a woman who had been meeting important world leaders for years. She dressed all in black and clutched a black briefcase in her left hand, dark tones that all drew attention to the red lapel pin over her heart emblazoned with the faces of her smiling father and grandfather.

As she approached the building's threshold, she paused and, out of the corner of her eye, looked to her left. Then she slowed her gait to allow the man by her side -- a nonagenarian named Kim Yong Nam who was North Korea's ceremonial head of state at the time -- to enter first, adhering to Confucian values of respecting one's elders despite the fact her family is revered with near religious fervor back home.

Park Ji-won, a former South Korean lawmaker and presidential chief-of-staff, said after four meetings with Kim Yo Jong, he came away with the impression of a woman whose intelligence and quiet confidence was beyond her years.

"She takes after her father and brother," said Park. "She is very smart and quick thinking. She is courteous, yet speaks her position clearly."

But the trip also set the stage for something else, a development that's only become clear in the past several days: that Kim Yo Jong was about to become the boss when it came to North Korea's relations with South Korea and arguably the second-most powerful figure in her country, answerable only to Kim Jong Un.

'The future of unified prosperity'

The group of North Korean defectors had hoped that by meeting in the middle of the night, they would avoid the prying eyes of nearby police, soldiers or passers-by who might take issue with what they were about to do.

They were on a mission to bring information about the outside world to their former countrymen. North Koreans are forbidden from consuming any information that's not approved by Pyongyang's strict censorship apparatus.

Then they let the balloons float into the sky, anticipating that as the sun rose, the wind would push the contraband toward their former home.

"What scares North Korea the most is the truth about themselves, the truth about their regime, the truth about the outside world," said Chun Yung-woo, a former South Korean diplomat. Chun led his country's delegation at the Six Party Talks, a multilateral effort to get North Korea to denuclearize, from 2006 to 2008.

Any insults against the Kims are tantamount to blasphemy, Chun explained, and require a full-throated response.

That responsibility fell to Kim Yo Jong.

Kim said the leaflets were a direct violation of the agreement reached at the Inter-Korean summit in April 2018, the very meeting she laid the groundwork for during her Olympic visit. As part of the deal, both leaders agreed to cease "all hostile acts and eliminating their means, including broadcasting through loudspeakers and distribution of leaflets" along their shared border.

She demanded the South Korean government punish the defectors, whom she called "betrayers," "human scum" and "riffraff who dared hurt the absolute prestige of our Supreme Leader representing our country and its great dignity," according to a statement carried by North Korean state news agency KCNA.

The South Korean government said it has asked police to investigate the defectors, but muzzling them could set a bad precedent in a liberal democracy where citizens enjoy freedom of speech.

However, it became clear this week that North Korea was truly upset.

Thirty months ago, on that brisk February day when Kim Yo Jong walked into the Blue House, she thanked Moon Jae-in for caring if she was too cold at the opening ceremony and writing in the residence guest book that she looked forward to a "future of unified prosperity."

Fanning the flames

A lot can happen in 30 months, and while the leaflets surely had North Koreans heated, most experts believe they're a spark that could lead to an inevitable breakdown in relations.

That summit took place at the end of February 2019, more than a year after Kim Yo Jong visited South Korea. By that point, her brother had already met Moon Jae-in, Chinese President Xi Jinping and in a historic first, President Trump. But despite the apparent breakthrough, working-level talks between Washington and Pyongyang failed to yield any progress on a deal trading North Korea's nuclear weapons program for sanctions relief.

Since it came to light that the Kim family was pursuing nuclear weapons about 30 years ago, four different US administrations have tried and failed to get them to abandon the program. While the carrots have differed, the sticks have always involved sanctions.

So when Trump and Kim decided to meet in person again, both hoped their second summit could help their respective sides find common ground.

But as they haggled in Hanoi over which nuclear facilities to trade and how much they were worth in terms of sanctions relief, it quickly became clear that there was a wide gap.

Both parties abruptly left when they realized they were not going to be able to agree on the contours of a deal in just several hours.

Lower-level talks have gone nowhere since, and North Korea believes it has been hoodwinked.

Statements published by important North Korean political figures paint the country as the aggrieved party, a nation that the United States and South Korea took advantage of for their own domestic political gains. This narrative ignores the fact that most experts believe the steps North Korea has taken so far are largely symbolic and do not preclude the regime from continuing to develop fissile material and further refine its nuclear weapons and ballistic missiles.

But the US-led sanctions that are strangling North Korea's economy are still in place. The South Koreans, who were supposed to provide economic assistance and cooperation, are still refusing to do so in order to abide by international law and avoid running afoul of the United States.

"(The) North Koreans are very disappointed that the diplomacy with the United States and South Korea has not yielded what they promised the North Korean people ... a better living standard" said Joseph Yun, the former US special representative for North Korea policy.

Yun said the North Koreans "need to explain to their own people" why "their big diplomatic initiative has not yielded anything."

The job seems to belong to Kim Yo Jong. And while she may be new to the game, she's playing it like an old North Korean pro.

Manufacturing crisis

Experts have for years accused North Korea of manufacturing crises either to create a sense of urgency in negotiations, to gain the upper hand in talks, or to sow discord between the United States and South Korea.

After the Soviet Union and the United States divided Korea in two, the North became a communist state and the South a capitalist one -- each backed by the rival side in the Cold War. When the Soviet Union collapsed, the North Koreans were left without a powerful benefactor, while the South Koreans could still rely on a global superpower and treaty ally for protection thanks to the thousands of American troops and modern weaponry stationed on the Korean peninsula.

Experts say that one of North Korea's key objectives is to level the playing field. And what better way to do that than create chaos driving a wedge between Washington and Seoul?

The Kim family may be genuinely upset about the leaflets, but it's clearly taking a page out of Pyongyang's old geopolitical playbook in an attempt to force the South Koreans to, as former top State Department Asia expert Evans Revere described it, "put something really appetizing on the table, if you will."

"You see the North Koreans engaged in a very interesting attempt to hold the South Korean government's feet to the fire by increasing the intensity and the level of their other rhetoric against South Korea," Revere said.

Today, Moon must play a particularly difficult balancing act, because his options for carrots are extremely limited -- almost everything the North Koreans want from South Korea runs afoul of sanctions spearheaded by South Korea's treaty ally, the United States.

"The North Koreans are pretty smart in how they play this game, and if they can not only get South Korean concessions -- and they're off to a good start -- but if they can also drive a wedge between Washington and Seoul, that's a pretty good day's work," Revere said.

The latest major play came Tuesday, when Kim Yo Jong gave the order to destroy the joint liaison office in the city of Kaesong, a city in North Korea where Seoul and Pyongyang have worked together on projects during times of peace.

Kim had hinted in a statement days earlier that the office, which had sat idle for months, would be "completely collapsed." No one outside of North Korea could be sure if that was a metaphor or meant the building would literally be blown to bits until they heard the actual boom.

The building was paid for by South Korean taxpayers and meant to facilitate dialogue and cooperation, so razing it was a bombastic symbol of North Korea's displeasure -- and a way to communicate that sentiment at a physical cost of only bricks and mortar.

It was a brilliant piece of theatrics, sure to grab the attention of the international media amid a global pandemic, rising racial tensions in the United States and a deadly conflict brewing on the border of the world's two most populous nations.

And, according to North Korean state media, the credit goes to Kim Yo Jong.

The youngest Kim takes center stage

When Kim Yo Jong was just a child, her father allegedly told a Russian diplomat that she had an aptitude for politics and predicted she might have a future in it.

History has proved Kim Jong Il right, and the headline-grabbing decision to demolish the joint liaison office is unlikely to be the last time the world hears from Kim Yo Jong.

"You see her every several months or so being given a new title, a new position, new responsibilities and checking all the key boxes to demonstrate her capacities and her responsibilities are growing," said Revere, the former State Department Asia expert.

"Not a day that goes by that some of the other newspapers don't have an article about some statement that's made and photographs of her."

But while the North Koreans hear more from Kim Yo Jong, they seem to be seeing less of Kim Jong Un.

The truth is unlikely to come out anytime soon. Kim Jong Un's health is one of North Korea's most closely guarded secrets, on par with the nuclear weapons program, because it has the potential to dent the carefully curated image of Kim as the infallible Supreme Leader.

Kim's sudden absence from the spotlight has precedent -- he disappeared for several months in 2014, reportedly after ankle surgery. But Kim is a leader known among his people for keeping a busy schedule and pounding the pavement. He's constantly photographed interacting with regular North Koreans, smiling alongside them and even hugging others.

For someone like that to just suddenly vanish from public view for weeks on end is unusual.

Some speculate she's filling the role of bad cop to her brother's good cop, allowing him the opportunity to swoop in and save the day. Analysts say getting into a fight with the South Koreans is a great way to boost a North Korean's street credentials as a tough fighter.

Others believe she's being propped up to become more than just a North Korean consigliere, but fill a role more like a vice president: a big player who enjoys the confidence of her brother and can help ease his workload.

But Kim Yo Jong and Kim Jong Un share an important connection. They lived together in Switzerland and at home, surrounded by adults and handlers. Their childhoods were remarkable but uniquely solitary and lonely. They lost their mother at a young age and their father as young adults.

All they endured, they endured together.