Police and military personnel blocked about 80 defectors from North Korea who had planned to send 200,000 leaflets by balloons Monday from Imjingak, near the Demilitarized Zone, Yonhap News Agency reported.
"We have placed an entry ban on civilians and vehicles taking into consideration safety concerns over North Korean warnings, clashes between anti- and pro- civic groups and complaints from residents," a Gyeonggi Regional Police Agency official said
On Friday, North Korea said its army would launch a "merciless military strike" in retaliation if it detected an effort to drop the literature. South Korea said its military was prepared to "destroy" a North Korean attack if it occurred.
North Korea's threat to attack the area drew protests from the activists, who have conducted similar balloon launches before. The country's threat of an attack is the first since Kim Jong Un became North Korea's leader in December.
"North Korea's threat is aimed at instigating division between people in the South," said Park Sang-hak of the Fighters for Free North Korea, the group that organized the event.