South Korean police block a highway near the border, stopping activists from sending propaganda leaflets to the North.<br/> <br />Protesters had planned to launch anti-Pyongyang leaflets across the border using balloons.<br/> <br />But they were banned after North Korea threatened to attack if the launch went ahead.<br/> <br />Despite the warnings, the group, led by North Korean defector Park Sang-hak, urged the authorities to let them carry on.<br/> <br />SOUNDBITE: ANTI NORTH KOREAN PROTEST LEADER PARK SANG-HAK SAYING (Korean):<br/> <br />"Our aim is to send letters containing truth and facts to our 20 million North Korean brothers. Why does President Lee stand by Kim Jong-il and Kim Jong-un and stop us?"<br/> <br />A group of anti-war demonstrators joined the altercation, calling for leafleting to stop as it threatened the South's safety.<br/> <br />The government condemned the leaflet launch, and called for restraint.<br/> <br />Amid rising tensions on the border, South Korea says it will retaliate against any attack from the North.
