Balloons take tech war to North Korea
Some anti-North Korean activists firmly believe the best way to defeat Kim Jong-un's regime is to break the cycle of propaganda served up every day to those living north of the border.
In recent years balloons have been used to carry leaflets from the south criticising the regime in the north.
Balloons are now being packed with technology including memory sticks and DVDs. The media contains South Korean soap operas and a cut-down version of The Interview, the controversial Seth Rogen film described by Pyongyang as an "act of war".
BBC Click's Dave Lee met some of the activists and joined them for a night-time balloon launch.