This North Korean defector sends ‘smart’ balloons back home. Here’s a look inside his secretive assembly room

Seoul, South Korea CNN —

Beside a desk scattered with soldering pieces, loose wires and electronic parts, Choi’s computer screen tracks wind conditions and the GPS location of some unlikely parcels: massive “smart” balloons he has sent floating into North Korea.

From a small apartment in South Korea’s capital, Choi, who CNN is identifying by a pseudonym for his privacy and safety, is one of the parties engaged in what has become a tit-for-tat balloon feud between the two Koreas, heightening tensions on the Korean Peninsula.

For many years, South Korean activists and North Korean defectors have sent balloons to the North, loaded with propaganda material criticizing dictator Kim Jong Un and USB sticks filled with K-pop songs and South Korean television shows – all strictly prohibited in the impoverished, highly isolated nation.

In response, North Korean authorities have sent more than 1,000 balloons toward the South since May carrying trash, waste and worms – fueling tensions as Kim Yo Jong, the powerful sister of North Korea’s leader, warned of “trouble” ahead.

Choi pictured in the apartment rented by his activist group as a base of operations. A portion of this image has been obscured to protect the subject's identity.

In 2020, South Korea passed a law criminalizing the sending of anti-North Korean propaganda leaflets over the border as the previous liberal government in Seoul pushed for engagement with Pyongyang.

But many campaigners defied the ruling before it was struck down by a court last year, which called the law an excessive restriction on free speech, in response to a complaint filed by North Korean defector-activists in the South.

Choi, co-founder of the Committee for Reforming and Opening North Korea, is