North Korean defector's mission to save his country "I want to rescue these people out of the country," Dr. Lee Min-bok says.

SEONGDONG-RI, South Korea -- When Kim Jong-un threatens South Korea or even the United States with his armed forces, it’s often the exaggerated threat of an unmatched army of 1 million trained soldiers -– but experts say they are concerned that if war broke out, the soldiers of the Korean People’s Army, brainwashed after years of propaganda, would fight to the death.

One man is trying to change that, one balloon at a time.

Dr. Lee Min-bok lives on the South Korean side of the world’s tensest border, in an aluminum structure with his wife, his weather-tracking data, and his leaflets.

Whenever the wind is right, he rushes out to blow up an enormous helium balloon, tied to hundreds of leaflets that combat the propaganda machine of the North. With facts about how wealthy and advanced South Korea is compared to the North, Lee’s leaflets encourage North Koreans to think for themselves, reconsider their circumstances, and rise up.

“These leaflets are decisive for the people in the North, to educate them and see the truth,” Lee told ABC News Chief Global Affairs Correspondent Martha Raddatz through a translator. “I am giving them the possibility to change and to revolutionize the regime.”

But how can Lee be so sure that plastic sheets of paper could possibly change hearts and minds? Because one saved his life.

Born and raised in North Korea, he worked in agriculture as a professor. Like all North Koreans are taught, he revered the Kim family. But he first grew disenchanted in the late 1980’s after his attempts to innovate the farming techniques were denied, despite the reprieve it would have brought from famine and starvation.

Then, while in the fields one day, he discovered a small leaflet that simply described how North Korea invaded South Korea and began the Korean War -– a reality that defied the regime’s propaganda. He asked village elders who told him the truth.

“After reading the leaflet, I knew that the North Korean regime was all false, so I decided to flee to the South,” he said.

Staring across the river now, nearly three decades later, Lee says he feels like he’s looking at his hometown, looking at the family he left behind.

“I want to rescue these people out of the country,” he said, noting he still has family on the other side of the border.

To do that, he now tells his story in leaflets -- how the truth fell from the sky and saved his life. He wants to arm North Koreans with that same knowledge so that they will defy the regime -- a mission so dangerous that he travels with government minders at all times, four stone-faced South Korean men who move in a ring around him.

North Korea’s 25 million residents live in poverty and oppression, under a surveillance state that may force them to work, at times even to starve.

The United Nations has reported in 2014 that the regime is responsible for “systemic” and “widespread” human rights violations, including rape, torture, forced abortions, and enslavement.

“I just have to say one word,” Lee said when asked what life is life in North Korea: “It is slavery, mentally and physically.”