Don’t look up. South Korean authorities warned residents along the border with North Korea that an “air raid” was underway. But it wasn’t rockets that were incoming. Rather: floating overhead were more than 150 balloons carrying trash and what’s believed to be feces.
An emergency disaster text alert was sent across cities on Tuesday night, according to South Korean newspaper Hankyoreh, ordering residents to “refrain from outdoor activities and report [objects] to military bases when identified,” along with the message in English: “Air raid preliminary warning.”
The incursion comes days after North Korea warned it would retaliate against anti-Pyongyang leaflets sent over by activists in South Korea earlier this month.
South Korean news agency Yonhap reported that South Korea’s military detected the balloons flying and falling in various locations across the country from Tuesday evening to Wednesday morning local time, going as far as South Gyeongsang, a province more than 180 miles from the demilitarized zone border between the two countries.
The balloons appeared to carry trash—like plastic bottles, batteries, shoe parts, and even feces—a South Korea Joint Chiefs of Staff official said. The military is working with police to collect the materials for analysis, local paper Chosun Ilbo reported, and has advised residents not to come into contact with the droppings and instead report them to authorities.
“Tit-for-tat action will be also taken against frequent scattering of leaflets and other rubbish by [South Korea] near border areas,” North Korea’s vice minister of national defense said on Sunday. “Mounds of wastepaper and filth will soon be scattered over the border areas and the interior of [South Korea] and it will directly experience how much effort is required to remove them.”
South Korea’s military condemned the act, saying on Wednesday that the balloons “clearly violate international law and seriously threaten our people’s safety.”
It’s not the first time North Korea has flown in garbage through balloons: in 2016, it sent what were initially feared to be biochemical substances but eventually turned out to be cigarette butts and used toilet paper.
North Korean defectors and activists in South Korea have also flown balloons the other way with propaganda payloads for years, in hopes of convincing North Korean residents to stand up against Kim Jong Un’s totalitarian regime. Pyongyang has long bridled against the practice, which it has labeled “psychological warfare.”
Earlier this month, a group of North Korean defectors sent about 20 large balloons carrying some 300,000 leaflets criticizing Kim. The balloons also reportedly carried about 2,000 USB sticks containing K-pop content, including songs from members of Korean boyband sensation BTS. (Kim has called South Korean K-pop a “vicious cancer.”)
In a statement, Kim’s sister Kim Yo Jong said South Korea was “not entitled to criticize the freedom of expression” of North Koreans. “We have tried something they have always been doing, but I cannot understand why they are making a fuss as if they were hit by shower of bullets,” she said, adding that, going forward, North Korea would continue to respond to South Korean balloons spreading propaganda “on case-to-case basis by scattering rubbish dozens of times more than those being scattered to us.”
As tensions escalate between North and South Korea, experts emphasize that such exchanges of balloons remain far preferable to an exchange of missiles. Peter Ward, a research fellow at the Sejong Institute, told Reuters: “These kinds of grey zone tactics are more difficult to counter and hold less risk of uncontrollable military escalation, even if they’re horrid for the civilians who are ultimately targeted.”
More Must-Reads from TIME
- Why Trump’s Message Worked on Latino Men
- What Trump’s Win Could Mean for Housing
- The 100 Must-Read Books of 2024
- Sleep Doctors Share the 1 Tip That’s Changed Their Lives
- Column: Let’s Bring Back Romance
- What It’s Like to Have Long COVID As a Kid
- FX’s Say Nothing Is the Must-Watch Political Thriller of 2024
- Merle Bombardieri Is Helping People Make the Baby Decision
Contact us at letters@time.com