A set of loudspeakers on the South Korean side have annoyed North Korea. And North Korea shelled a South Korean military unit on the western section of the inter-Korean border to destroy the loudspeakers on Thursday. In response, the South fired “dozens of rounds of 155mm shells” towards the location the North had launched its rocket from, a Defense Ministry spokesman in Seoul told AFP.

North Korea Shells South Korea To Target Loudspeakers

South Korea evacuates the area

Pyongyang didn’t return the fire. Instead, they sent a letter to Seoul, warning that the South must take down those loudspeakers and dismantle them within 48 hours or face military action. According to the South’s Yonhap news agency, the South Korean military detected the trajectory of a North Korean projectile launched at 3:52 p.m. local time. However, it didn’t damage the loudspeakers or cause any injuries.

The shell landed in a mountainous area near the South Korean military base in Yeoncheon, a town north-west of Seoul. South Korean President Park Geun-hye told defense officials to “react firmly” to provocations by North Korea. On Thursday, South Korean military increased its alert status to the highest level. Geun-hye has also ordered evacuation of residents from the Yeoncheon area. Seoul is also holding an emergency National Security Council meeting over the shelling.

Why North Korea wants to destroy those loudspeakers

Tensions between North and South Korea heightened earlier this month when two South Korean soldiers were severely injured by a landmine explosion in the Demilitarized Zone. The South accused North Korea of planting the landmines, but Pyongyang has rejected the allegations.

After the incident, Seoul set up loudspeakers near the North Korean border to blast anti-Pyongyang propaganda. The two countries had halted that tactic in 2004. On Saturday, North Korea asked the South to stop broadcasting propaganda messages or face military action. On Monday, Pyongyang started its own broadcasts.

The fire exchange on Thursday comes as South Korea and the U.S. have started joint military exercises. North Korea condemned the joint military drills as “preparation for war,” even though the South maintained that the drills were defensive.