The sister of North Korean leader Kim Jong Un has called the South Korean defence minister a “scum-like guy” and warned the South may face “a serious threat” for talking about pre-emptive strikes on the North.

Kim Yo Jong’s statement came amid heightened tensions between the rival Koreas over the North’s spate of weapons tests this year, including its first intercontinental ballistic missile launch in more than four years.

During a visit to the country’s strategic missile command on Friday, South Korean Defence Minister Suh Wook said South Korea has the ability and readiness to launch precision strikes on North Korea if it detects the North intends to fire missiles at South Korea.

Seoul has long maintained such a pre-emptive military strategy to cope with North Korea’s growing missile and nuclear threats, but it was still highly unusual for a senior Seoul official under  president Moon Jae-in’s administration to publicly discuss it.

On Sunday, Kim’s sister, Kim Yo Jong, issued blistering rhetoric directed at Suh and threats toward Seoul.

“The senseless and scum-like guy dare mention a ‘pre-emptive strike’ at a nuclear weapons state,” Kim Yo Jong said in a statement carried by state media. “South Korea may face a serious threat owing to the reckless remarks made by its defence minister.”

“South Korea should discipline itself if it wants to stave off disaster,” she said.

Kim Yo Jong, a senior official in the North’s ruling Workers’ Party, is in charge of relations with Seoul and Washington. South Korea’s spy service says she is the North’s number two official behind her brother.

Pak Jong Chon, a secretary in the Workers’ Party’s central committee, separately warned that “any slight misjudgement and ill statement rattling the other party under the present situation” may trigger “a dangerous conflict and a full-blown war”.

Mr Pak said North Korea will “mercilessly direct military force into destroying major targets in Seoul and the South Korean army” if South Korea pre-emptively attacks North Korea.

Relations between the Koreas briefly flourished in 2018 after North Korea abruptly reached out to South Korea and the United States and expressed its willingness to put its nuclear programme on the bargaining table. At the time, Kim Yo Jong visited South Korea to attend the opening ceremony of the Winter Olympics and conveyed her brother’s invitation for Mr Moon to visit the North. Kim Jong Un and Mr Moon eventually met three times in 2018.

But North Korea turned a colder shoulder on Mr Moon and cut off ties with South Korea after its broader diplomacy with the United States collapsed in 2019 due to disputes over US-led economic sanctions on the North.