At least one North Korean balloon carrying trash landed on the grounds shared by the South Korean presidential office and the National Defense Ministry in Yongsan, central Seoul, on Wednesday morning.

South Korea’s Presidential Security Service said that some trash dropped by the North Korean balloon was identified on the grounds of the Yongsan presidential office and the adjacent defense ministry.

The balloon contained mostly scraps of paper and plastic, according to the South Korean military.

The Security Service said that its Chemical, Biological and Radiological response team found in its primary analysis that the North Korean waste materials did not appear to be hazardous, and that they had been collected accordingly.

The Security Service said that together with the Joint Chiefs of Staff it was keeping up monitoring and surveillance of the balloons possibly entering the skies over the presidential office.

Wednesday marks the tenth time this year that North Korea dumped trash across South Korea using balloons.

To minimize damage, the South Korean military says it is most effective to pick up the balloons and their contents after they reach the ground rather than taking them down mid-air.

The last time the North Korean balloons were known to have flown past Yongsan was June 9, several of which fell near the presidential office.

Four-star general-turned-lawmaker Rep. Kim Byung-joo of the Democratic Party of Korea previously claimed that the balloons crossing the flight restriction zone over Yongsan indicated a “failure” of the Security Service.

“The no-fly zone around the Yongsan presidential office had been infiltrated by North Korean balloons,” he said June 10 in a radio interview.

Some say the South Korean government could do more to dissuade activist groups from flying anti-Pyongyang leaflets over the border as a way of placating North Korea to stop sending balloons.

Democratic Party Rep. Boo Seung-chan, former Defense Ministry spokesperson, told The Korea Herald that as North Korea seemed to be using the balloons to retaliate against South Korean leaflets, some restraint on leaflet activism “might be the answer.”

“Both sides have to make efforts to make peace at the end of the day,” he said.

Shin Won-sik, the South Korean defense minister, said the military was preparing for the possibility North Korea could engage in other types of provocations such as cyberattacks and GPS signal jamming in response to the leafleting.

“Our military is prepared for all types of provocations that North Korea could launch under a robust South Korea-US joint defense posture,” he said in a recent interview with Japanese daily Yomiuri Shimbun.