SEOUL/PAJU, Oct. 22 (Yonhap) -- South Korea's military is on high alert Monday after North Korea threatened to strike a border area if anti-Pyongyang activists fly propaganda leaflets from there into the communist nation later in the day.
The Fighters for Free North Korea, a civic group composed of North Korean defectors, plan to send 200,000 leaflets by balloons from Imjingak near the Demilitarized Zone at 11 a.m despite drizzling rain, according to the event organizer, Park Sang-hak.
It is not clear whether the activists will be able to hold the event as planned, as the military and police have banned civilian entry into Imjingak since 8:40 a.m., including tourists, residents and journalists.
They will lift the restriction after the situation is deemed over, according to officials.
On Friday, North Korea said its army will launch a "merciless military strike" if any move to drop leaflets is detected. South Korea's defense minister reacted swiftly, saying his military is prepared to "completely destroy" the origin of a North Korean attack if it occurs.
"Our military units near Imjingak are maintaining readiness to immediately return artillery fire," a senior military official said, asking for anonymity, as he is not allowed to talk about military information. "We are closely watching the North Korean military's movements."
The South Korean military has stepped up combat readiness by deploying artillery and tank brigades and combat air patrols by F-15K and KF-16, according to the official.
The North Korean threat came a day after South Korean President Lee Myung-Bak made a surprise visit to the front-line island of Yeonpyeong in the tensely guarded Yellow Sea, which was shelled nearly two years ago by the long-time rival.
Civic groups in the South have sent anti-Pyongyang leaflets in the past, but the communist state's unusually strong threat of an attack is the first since North Korean leader Kim Jong-un succeeded his father Kim Jong-il last December.
Pyongyang has condemned the leaflet drop as psychological warfare and an attempt to topple its communist regime, warning it could ignite a war on the Korean Peninsula, though it did not actually launch an attack.
The two Koreas still remain technically at war, as the 1950-53 Korean War ended in a truce, not a peace treaty.