Some ten members of Fighters for Free North Korea (FFNK), a Seoul-based group of North Korean defectors, released 10 giant, gas-filled balloons carrying some 200,000 leaflets across the heavily-fortified border to the North.
The leaflets criticise the Kim dynasty including current leader Kim Jong-Un and blame them for the vast gap between the impoverished, isolated North and economically advanced South.
The latest leaflet launch came a day after the North issued angry warnings that it would "attack the source of provocation".
The North, whose citizens are barred from accessing outside information including the Internet, has always reacted angrily to such launch of leaflets.
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It made an unusual move last week by sending a rare message to the South Korean president's office, demanding an end to such anti-Pyongyang leaflets.
"Despite all the blackmail and threats, we will continue to send the letters of truth until the North's people achieve freedom," FFNK leader Park Sang-Hak said after releasing the balloons today from the border city of Paju.
But a group of left-wing activists held a separate protest near the launch site, urging them to stop the action and accusing them of escalating tension on the peninsula.
Today's launch came as the Asian Games were underway in the South Korean port city of Incheon, with 150 North Korean athletes taking part.
The rare visit by North Koreans to the South came after months of tortuous negotiations between the two sides amid high military tensions.