The Republic of Korea is preparing to escalate its psychological warfare against the Democratic People's Republic of Korea in response to its latest nuclear test with giant electronic message boards along the border.

Seoul has already set up walls of loudspeakers on the border that have been blaring bursts of anti-DPRK slogans and "K-pop" music since Friday, a tactic Pyongyang considers insulting.

ROK's defense ministry said on Thursday it was preparing to install the old electronic bulletin boards, which media said were last used in 2004.