Seoul's defense ministry said Wednesday that it spotted extra activity at the North's heavy artillery units on the border near the location of South Korea's loudspeakers.
Some experts say the communist regime is preparing to fire at the speakers.
The ministry says it's keeping a close eye on the recent artillery movements to determine if the recent exercises are aimed at targeting the speakers.
Psychological warfare is being conducted on both sides of the border using loudspeakers to broadcast propaganda.
Pyongyang's mine detonations on the southern side of the military demarcation line that severely injured two South Korean soldiers earlier this month resulted in the South resuming, after 11 years, its use of loudspeakers to broadcast propaganda over the border.
North Korea has demanded that the South tear down its loudspeakers or risk indiscriminate attacks as a consequence.
Both the U.S. State Department and the Pentagon on Tuesday local time slammed North Korea for the explosions, calling the incident a violation of the armistice agreement.
The U.S. says it's keeping a close eye on any sort of unusual movements and warned North Korea that any further provocations would further it from the international community.
Kim Hyun-bin, Arirang News.