South Korea's Joint Chiefs of Staff (JCS) said it will handle any provocation by the North with "powerful and firm" measures, Yonhap reported.
"A civic group's scattering of leaflets is a part of its rights to free speech, and we clearly state once again that it is those people's judgment call to make and cannot be restricted by force," the JCS said in a release.
The remarks came after North Korea threatened to use all power to destroy the anti-Pyongyang fliers to be released by the civil group across the border.
Park Sang-hak, head of the activist group, said earlier this month he and other North Korean defectors would release balloons holding 500,000 leaflets, as well as DVDs of the U.S. film "The Interview," a comedy depicting a fictitious assassination of the North's leader Kim Jong-un.