Pyongyang, North Korea - North Korea on Friday threatened the South with a "terrible response" if it detects any more drones buzzing across the border after repeated incursions.

South Korean President Lee Jae Myung has sought to repair ties with North Korea since taking office last year, criticizing his disgraced predecessor for sending drones to scatter propaganda over Pyongyang.

But North Korea claims it shot down a surveillance drone just last month, an incident which threatens to blight Lee's efforts to patch things up.

Kim Yo Jong, the powerful sister of North Korean leader Kim Jong-un, warned of severe repercussions if the drones did not stop.

"I give advance warning that reoccurrence of such provocation as violating the inalienable sovereignty of the DPRK will surely provoke a terrible response," Kim said in a statement carried by Pyongyang's official Korea Central News Agency.

"We don't care who the very manipulator of the drone infiltration into the airspace of the DPRK is and whether it is an individual or a civilian organization," she added, using the acronym for North Korea's official name.

Seoul initially denied any official involvement in the January drone incursion, with officials suggesting it was the work of civilians.

But a joint military-police task force announced earlier this week it was investigating three active-duty soldiers and one spy agency staffer in an effort to "thoroughly establish the truth."

Seoul's unification minister Chung Dong-young expressed "deep regret" earlier this week.

Chung has previously suggested the drone may have been the work of government staffers still loyal to former hardline leader Yoon Suk Yeol, who staged a failed self-coup in 2024 that also aimed at provoking a military confrontation with the North.

Kim Yo Jong said that Chung's conciliatory remarks were "quite sensible behavior."

South Korea's unification ministry responded to Kim's statement, vowing to "immediately implement preventative measures to prevent similar incidents from recurring."