North Korea has announced it will resume anti-South Korea propaganda loudspeaker broadcasts along the entire length of its heavily fortified border with the South, with Kim Yo Jong, the sister of leader Kim Jong Un, saying the speakers will be operational within October.

Kim Yo Jong, one of the most senior figures in Pyongyang and her brother's top spokesperson on relations with Seoul and Washington, made the initial announcement on Wednesday following a visit to front-line fortification areas. In a follow-up statement on Thursday, she said loudspeakers would be placed on standby "within days."

"Our tactical hunting teams are taking new positions, and within October, the loudspeakers for psychological warfare against the ROK will be in operation along the whole border," Kim said, using the initials of South Korea's formal name, the Republic of Korea.

The announcement marks a significant escalation in inter-Korean tensions. South Korean President Lee Jae Myung had suspended broadcasts from the southern side just days into his presidency in June 2025 as a confidence-building measure, and the military dismantled its fixed border loudspeakers in August of that year. North Korea subsequently suspended its own broadcasts. If resumed, the loudspeaker exchanges would be the first across the border in 16 months.

Kim conducted her border inspection alongside Marshal Pak Jong Chon, one of Kim Jong Un's top military officials. She described the ongoing fortification work as a "sacred and great undertaking" in support of her brother's policy of permanently severing ties with South Korea, which he has declared his most hostile adversary.

"Our military leadership underlined the need to make those rogues aware that our new firepower units have taken their firing positions," Kim told soldiers during the visit, reminding them of Kim Jong Un's order to make the border with the "enemy ... eternally impregnable."

She also warned Seoul of "the most horrible and distressing situation" if it continues what Pyongyang describes as interference in North Korea's internal affairs. Kim further warned that if South Korean warning shots cause "actual harm to our territorial security and our service persons' safety," North Korean border guards "will show no mercy for the armed gangsters bereft of reason."

The escalation follows a landmine blast on September 21 that injured three South Korean soldiers south of the military demarcation line, two of them seriously. Following an inspection with the United Nations Command, which oversees the 1953 armistice that halted but did not formally end the Korean War, Seoul formally attributed the blast to North Korean-planted mines and called it an armistice violation. Pyongyang denied responsibility, calling the incident a "self-staged farce" and a South Korean fabrication.

Seoul's Foreign Ministry said on Thursday it would send a letter to the UN Security Council asserting that the blast was caused by North Korean mines and constituted an armistice violation. The letter will demand an apology from Pyongyang and urge dialogue to prevent further escalation.

North Korea has been reinforcing its side of the demilitarised zone with mines, barbed wire fences and anti-tank barriers since Kim Jong Un declared in December 2023 that the two Koreas were "two states hostile to each other." South Korea's military says North Korean soldiers have crossed the military demarcation line 50 times this year during fortification work, prompting South Korean troops to respond with warning shots and loudspeaker broadcasts. North Korea has denied the border crossings, calling them a "false pretext," and accused Seoul of provocations that have increased "beyond the red line" since the mine blasts.

During the border inspection, Pak Jong Chon accused South Korea of making "deliberate, premeditated and absurd" claims to shift blame for the rising tensions and threatened an "overwhelming response" to any South Korean provocations.

South Korea's Joint Chiefs of Staff chairman, Jin Yong-Sung, called Kim Yo Jong's threats "intolerable" and ordered the military to "sternly respond" to potential provocations. South Korean Defence Ministry spokesperson Chung Binna said Seoul would need to take "proportionate measures" in response to the North's moves, but did not elaborate on what steps were being considered.

South Korea's military and Ministry of Unification also urged Pyongyang to return to talks to resolve differences. Lee has pursued a policy of diplomatic engagement since taking office, despite Pyongyang's continued refusal to resume dialogue.

South Korean military observers had noted routine maintenance activity on North Korea's loudspeaker infrastructure before Kim Yo Jong's statements were issued.

Both Koreas have historically used giant loudspeakers to broadcast propaganda across the border. In recent years, North Korea has broadcast haunting sounds, while South Korea has used K-pop music and news critical of Pyongyang.