On Monday South Korean police blocked activists who were trying release balloons carrying propaganda to North Korea after Pyongyang threatened to attack if they were allowed to do so.
Police and troops in the South blocked motorway exits to the launch site close to the border which separates the impoverished North from its wealthy neighbour.
Park Sang-Hak an anti-North Korea activist said:
“Our aim is to send letters containing the truth to 20 million of our North Korean brothers. So why does does the President of South Korea stand by Kim Jong-il and Kim Jong-un and stop us?”
The two nations are still technically at war following their 1950-53 conflict so the heavily militarised border remains tense.
The South Korean unification ministry asked the defectors and anti-North Korea activists who frequently launch balloons carrying propaganda and money across the border to “exercise self restraint”.
Friday’s threats of military action were the first from North Korea since Kim Jong-un came to power in December 2011.