South Korea’s military on Monday warned of “corresponding measures” in response to North Korea threatening to fly an uncrewed aerial vehicle over Seoul.

“If a North Korean UAV infiltration takes place, we will be taking corresponding measures to protect the safety and property of our people,” Joint Chiefs of Staff spokesperson Col. Lee Sung-jun said.

The JCS spokesperson dismissed accusations by North Korea that the UAVs that flew over Pyongyang earlier this month had taken off from Baengnyeongdo, a South Korean island near the sea border with the North.

“Such unilateral claims are not worth confirming or responding to,” he said. He added that several North Korean UAVs had trespassed into South Korean skies in the past decade, but the North had shown no sign of regret.

Kim Yo-jong, North Korean leader Kim Jong-un’s sister, threatened to send a UAV over Seoul and drop propaganda leaflets against President Yoon Seok Yeol in a statement carried by the Workers Party’s official newspaper, Rodong Sinmun, on Monday.

“I would like to see how the dirty dogs of Seoul would bark and bite foaming at the mouth under such circumstances,” she said.

The North Korean Defense Ministry announced the results of its investigation of what it called a “gross violation of sovereignty by South Korean UAVs,” in Rodong Sinmun the same day.

The North’s Defense Ministry claimed that at around 11:25 p.m. on Oct. 8, a UAV took off from the South Korean island of Baegnyeongdo and flew over seas near South Hwanghae Province before changing its course to reach Pyongyang.

Disclosing what it insists was the trajectory of a South Korean UAV on the night of the supposed incursion, it said, “This is clearly a work of the South Korean military.”

But the claims raised Monday deviate from earlier claims made by the North Korean Foreign Ministry which said that the alleged South Korean UAV infiltrations took place on Oct. 3, 9 and 10.

According to an analysis by Rep. Yu Yong-weon, a member of the National Assembly National Defense Committee, the surveillance UAVs owned by the South Korean Drone Operations Command are not capable of making the trip to and from Pyongyang because of their limited flight time and range.

On North Korea continuing to launch balloons loaded with trash toward the South, the JCS spokesperson said at Monday’s briefing there will be “military measures” in the event South Korean lives and properties are threatened.

Last week, North Korea flew balloons carrying leaflets targeting Yoon and his wife Kim Keon Hee for the first time since it began the trash balloon campaign in May. Many of them landed within the presidential office compound in Yongsan, central Seoul.

While North Korea has claimed its trash balloon launches are in response to South Korean activists sending anti-Kim Jong-un leaflets, the National Intelligence Service in Seoul says the two are not correlated.

“Leaflet activism does not appear to be linked to North Korean filth balloon releases. North Korea appears to be floating the balloons on an arbitrary schedule, with no discernible pattern,” the South Korean intelligence said in the analysis obtained by The Korea Herald.