South Korean activists and defectors launched giant balloons containing tens of thousands of propaganda leaflets into North Korea on Wednesday, as Pyongyang mourned the death of longtime leader Kim Jong-il.

The leaflets sent by a small group of activists gathered at the border are sure to infuriate the North, which views such actions as propaganda warfare. The leaflets contained messages opposing another hereditary power transfer in North Korea, as well as portraits of Kim Jong-il and heir Kim Jong-un.

North Korea has previously warned that it would fire at South Korea in response to such actions, and Wednesday’s balloon launch comes at an extremely sensitive time for North Korea.

Kim Jong-il died of a heart attack on Saturday caused by overwork and stress, according to North Korean media.

A state funeral is set for December 28, 2011 in Pyongyang, to be followed by a national memorial service the next day, according to state media. North Korean officials say they will not invite foreign delegations and will allow no entertainment during the mourning period.

Activists vowed to send more leaflets later Wednesday.

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