Several trash-carrying balloons from North Korea landed on the presidential office compound in Yongsan District, Seoul, Wednesday, sparking concerns about potential security lapses in South Korea’s defense against unconventional provocations from Pyongyang.

This is the first time the trash-laden balloons have landed on the presidential compound, out of over 2,000 balloons Pyongyang sent on 10 occasions since late May.

The persistent balloon launches are proving to be a major headache for the South Korean military, which appears to lack an effective strategy to deter them other than repeatedly collecting the debris from the ground.

In a text message sent to reporters at around 7:25 a.m., the Joint Chiefs of Staff (JCS) said the balloons launched by North Korea 한국을 appeared to be heading toward northern Gyeonggi Province, and urged residents to be wary of falling objects.

The military detected around 300 balloons in the air, with approximately 250 falling within South Korea’s territory, mostly in Seoul and the surrounding Gyeonggi Province.

The Presidential Security Service (PSS) said some balloons landed on the presidential compound, but did not specify the exact number.

“Following an investigation by the chemical, biological, radiological, and nuclear response team, it was confirmed that the objects posed no risk or contamination and were subsequently collected,” the PSS said.

The presidential office said it had been monitoring the balloons’ precise location in real-time until they landed. It is unclear whether President Yoon Suk Yeol was in the office when the balloons landed, but his office said earlier that he had no official appointments on Wednesday.