Garbage transported by a North Korean balloon once again falls onto the presidential compound in Seoul

SEOUL, South Korea (AP) — Garbage carried by a North Korean balloon fell on the presidential compound in central Seoul for the second time Thursday, raising concerns about the threat to key South Korean sites.

The incident came after the rival Koreas stepped up their threats and rhetoric against each other as North Korea claimed that South Korea had flown drones over its capital Pyongyang this month to distribute propaganda leaflets.

No dangerous items were found in the trash that fell to the ground when one of North Korea's balloons burst over the South Korean presidential compound on Thursday morning, South Korea's presidential security service said in a statement.

North Korea has sent thousands of balloons containing bags of trash such as plastic and paper trash to South Korea since late May, resuming a Cold War-style psychological campaign. The garbage that fell on the South Korean presidential compound in July also did not contain any hazardous substances.

It was not immediately known whether South Korean President Yoon Suk Yeol was at the site during the latest incident. Later on Thursday, he met visiting Polish President Andrzej Duda in his office.

South Korean media reported that North Korean leaflets criticizing Yoon and his wife Kim Keon Hee were found on Thursday in Seoul's Yongsan district, where Yoon's presidential office is located. The media published photos of some leaflets describing Kim as a modern-day Marie Antoinette, the queen who was beheaded in 1793 during the French Revolution.

The reports said it was the first time that North Korean propaganda leaflets had been found in South Korea since the North began its balloon campaign five months ago.

South Korea's presidential security service did not confirm the reports. But South Korea's chiefs of staff later urged North Korea to stop flying “crude leaflets” slandering the South Korean president and warned that Pyongyang would be solely responsible for any consequences.

Experts say North Korea likely doesn't have the sophisticated technology needed to drop balloons at specific targets.

“Whether the balloons have GPS or not, it's about launching them in large numbers and reaching the right altitude depending on the wind direction and speed so that they can take advantage of those winds on their journey,” says Lee Choon Geun, volunteer Research Fellow at South Said Korea Institute of Science and Technology Policy.

“While some media outlets say the accuracy of the balloons has improved, this improved accuracy is not because they have been equipped with any kind of guidance system, but rather because it is the time of year when the wind blows southward,” said Lee.

North Korea accused South Korea of ​​using drones to drop propaganda leaflets over Pyongyang three times this month and threatened a military response if it happened again. South Korea has refused to confirm whether it sent drones but warned that North Korea would face the end of its regime if the safety of South Korean citizens was threatened.

North Korea said its balloon activities were a countermeasure against South Korean activists who fired anti-Pyongyang leaflets from their own balloons. South Korea responded by resuming propaganda loudspeaker broadcasts in border areas, prompting North Korea to turn on its own front speakers.

Korea's Cold War-style campaigns come at a time when North Korean leader Kim Jong Un has increased the pace of his weapons testing and expanded military cooperation with Russia.

U.S. and South Korean officials said Wednesday that 3,000 North Korean troops have been deployed to Russia and are training at multiple locations. South Korean officials say North Korea eventually wants to send a total of 10,000 troops to Russia to support its war effort in Ukraine.

South Korea fears that Russia could reward North Korea by providing it with sophisticated technologies that could improve the North's nuclear and missile programs targeting South Korea and the United States.