Can something as innocuous as a helium-filled balloon instigate regime change? North Korean-born Park Sang-hak believes so. For several years he has led a group of activists launching balloons into the South Korean skies. Their hope is that some will drift across the border into North Korea and release their payload: leaflets, USB sticks and DVDs containing propaganda-busting information.

His efforts have earned Mr Park the nickname “Enemy Zero” in North Korea. But even in South Korea the authorities step in to discourage the balloon launches. Their fear is the information the balloons carry might further escalate tensions between the two countries – particularly given that some of the most recent balloons have carried copies of Seth Rogen’s controversial film The Interview.

In this film from our colleagues at Click, Dave Lee of BBC News talked to Park to find out more about his plan to use technology to fight North Korea’s political regime – at a time when that regime is itself turning to technology and cyber attacks to make its mark on the international stage.

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