South Korea has vowed “resolute punishment” if North Korea escalates military tensions along their heavily fortified border, raising fears that a renewed propaganda war could spiral into a dangerous confrontation between the two rivals.

Seoul’s Defence Ministry issued the warning on Tuesday after Pyongyang signalled it was considering restarting loudspeaker broadcasts along the border and deploying “additional tactical weapons” near the frontier.

The threats, communicated through North Korean state media by Kim Yo Jong, the powerful sister of leader Kim Jong Un, offered few details about what weapons might be deployed. But the announcement has intensified concern over a border where even seemingly limited military incidents have previously brought the two countries close to armed conflict.

“If North Korea uses our legitimate measures as a pretext to carry out further provocations, we will punish it resolutely,” South Korea’s Defence Ministry said.

The ministry rejected Pyongyang’s accusations that Seoul had repeatedly fired warning shots and issued broadcasts under what the North described as an “unreasonable pretext”. South Korea said its actions near the Military Demarcation Line were “a legitimate defensive measure” intended to prevent incursions and force North Korean troops who cross the line to withdraw.

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Seoul urged Pyongyang to stop making what it called groundless claims, halt border crossings, and work to resolve disagreements over the demarcation line.

South Korea’s military leadership has also moved to reinforce readiness. Joint Chiefs of Staff chairman Jin Young-seung reviewed preparedness during a visit to a frontline army command, ordering operations designed to strengthen Seoul’s initiative in the Demilitarized Zone.

“We cannot tolerate North Korea falsely characterising our legitimate operational measures as provocations and shifting responsibility for heightened military tensions onto our military,” Jin said.

The confrontation unfolds against a deteriorating security environment along one of the world’s most heavily fortified borders. North Korea has expanded its frontline defences with mines, barbed-wire fences and anti-tank barriers as Kim’s government pursues a policy of severing ties with the South.

South Korea’s military has previously said North Korean soldiers crossed the Military Demarcation Line 50 times this year during fortification work.

The danger is not merely theoretical. In 2015, mine explosions blamed on North Korea severely injured two South Korean soldiers, prompting Seoul to resume loudspeaker broadcasts for the first time in 11 years and bringing the rivals close to armed conflict.

The broadcasts are an unusual but potent weapon of psychological warfare. North Korea has used sirens, drums and animal-like howls, while South Korea has aired news reports and K-pop music — material that challenges Pyongyang’s efforts to restrict its population’s exposure to outside information.

Since taking office last year, South Korean President Lee Jae Myung’s liberal government had halted the broadcasts in an attempt to improve relations. North Korea was subsequently reported to have begun dismantling its own loudspeakers.

That fragile de-escalation now appears increasingly vulnerable. A decision to resume broadcasts or introduce additional weapons could trigger a cycle of retaliation along a border where miscalculation carries serious consequences.

For Seoul, the challenge is to deter further North Korean provocations without allowing a local confrontation to become a wider military crisis. For Pyongyang, renewed pressure may serve its strategic aims — but it also risks reviving a dangerous contest that neither side can easily control.