South Korea and North Korea have stepped up their psychological warfare in response to the North's rocket launch by putting additional loudspeakers in place along their border, military officials said Wednesday.

Both sides have installed loudspeakers along their heavily fortified border to broadcast messages critical of each other.

North Korea is sensitive to such broadcasts because they could threaten the stability of the Kim Jong-un regime.

"Immediately after North Korea fired its long-range missile, we placed additional mobile loudspeakers in front-line areas and increased the length of the broadcasts," said a South Korean military official who spoke on the condition of anonymity.

North Korea launched a long-range rocket Sunday, drawing strong condemnation from the international community for what it sees as a test of its ballistic missile technology. The communist nation is banned under U.N. Security Council resolutions from conducting launches using that technology.

In response to the South's move, North Korea has also turned on mobile loudspeakers and continued to send anti-South Korea propaganda leaflets across the border inside balloons, officials said.

"We stand fully ready for the possibility of further provocations from the North," an official said. (Yonhap)