North Korea will cut communication with South Korean authorities, including military, after activists floated state criticism across the border in large balloons.
The Korean Central News Agency (KCNA) reported all cross-border communication lines would be "completely shut down" from midday (local time) on Tuesday.
The two countries have conducted routine phone calls each day since the coronavirus outbreak restricted face-to-face meetings, but even the hotline between the leaders Moon Jae-in and Kim Jong Un is to be ended.
In recent years, North Korean defectors and conservative activists have floated huge balloons carrying leaflets criticising leader Kim Jong Un over his nuclear ambitions and human rights record.
Although police in the South occasionally intervened to salvage political relations with the North, Seoul has typically cited the activists' freedom of speech in the demonstrations.
KCNA refers to the South as "the enemy" and follows recent threats nullify a 2018 inter-Korean tension-reduction agreement.
The end of the Korean War in 1953 failed to see a formal peace agreement between the two, meaning the countries technically remain at war.
However, the launch of the balloons from the South has been deemed "treacherous and cunning" enough to qualify as a "preemptive attack that precedes a war".
Seoul has not immediately responded to the decision, but recently said it will push for new legal steps to ban activists from launching leaflets.
The North claims that response lacks sincerity.
Cover image: Members of Fighters for Free North Korea, an organisation of defectors from North Korea, send balloons carrying anti-North leaflets across the border from the South Korean border city of Paju IN 2016 (Picture: Yonhap/PA).