North Korea's military is threatening to shoot down balloons that South Korean activists plan to send over the heavily militarized border carrying 10,000 DVDs of the Hollywood film The Interview.
Activists say they plan to launch copies of the film - a comedy about a fictional CIA plot to assassinate North Korean leader Kim Jon Un, along with 500,000 propaganda leaflets across the de-militarized zone on or around March 26.
Pyongyang's official Korean Central News Agency called the planned launch a "de facto declaration of war."
The South's military said it would retaliate if North Korea opens fire on the South's territory.
South Korean residents living near the border have complained the activists are putting local residents lives at risk by making them potential targets.