North Korea flew hundreds of balloons carrying trash and manure toward South Korea in one of its most bizarre provocations against its rival in years, prompting the South鈥檚 military to mobilize chemical and explosive response teams to recover objects and debris in different parts of the country.

The balloon campaign came as North Korean leader Kim Jong Un urged his military scientists to overcome and continue developing space-based reconnaissance capabilities, which he described as crucial for countering U.S. and South Korean military activities, state media said Wednesday.

In his first public comments about the launch failure, Kim also warned of unspecified 鈥渙verwhelming actions鈥� against South Korea over an exercise involving 20 fighter jets near the inter-Korean border hours before North Korea鈥檚 failed launch on Monday. In a speech Tuesday, Kim described the South Korean response as a 鈥渉ysterical attack formation flight and strike drill鈥� and 鈥渄irect military challenge鈥� toward North Korea, the North鈥檚 official Korean Central 亚洲天堂 Agency said Wednesday.

South Korea鈥檚 Joint Chiefs of Staff said North Korea also has been flying large numbers of trash-carrying balloons toward the South since Tuesday night in retaliation against South Korean activists for across the border.

The South鈥檚 military said about 260 North Korean balloons were found in various parts of the country as of Wednesday afternoon and were being recovered by military rapid response and explosive clearance teams. The military said the balloons brought various types of trash and manure but so far they had found no human excrement. It advised civilians not to touch the objects from North Korea and to report to military or police after discovering them.

In a statement issued over the weekend, North Korean Vice Defense Minister Kim Kang Il said the North was planning to scatter 鈥渕ounds of wastepaper and filth鈥� over border areas and other parts of South Korea, in what he described as 鈥渢it-for-tat鈥� action against the leafletting by South Korean activists.

Later Wednesday, Kim Yo Jong, the North Korean leader鈥檚 powerful sister, took to state media to ridicule a South Korean military statement demanding that the North stop its 鈥渋nhumane and vulgar activity.鈥� She said the North was merely exercising its freedom of expression, which the Seoul government has stated as a reason for its inability to stop anti-North Korean activists from flying leaflets across the border.

鈥淥nce you experience how nasty and exhausting it feels to go around picking up dirty filth, you will realize that you shouldn鈥檛 talk about freedom of expression so easily when it comes to (leafletting) in border areas,鈥� she said. 鈥淲e will make it clear that we will respond with tens more times the amount of filth to what the (South Koreans) spray to us in the future.鈥�

Photos released by the South Korean military showed trash scattered across highways and roads in different parts of the country. In the capital, Seoul, military officials found what appeared to be a timer that was likely designed to pop the bags of trash midair. In the central South Chungcheong province, two huge balloons carrying an un-popped plastic bag filled with dirt-like substances were seen at a road.

There were no immediate reports of damage caused by the balloons. Similar North Korean balloon activities damaged cars and other property in 2016.

Kim Jong Un鈥檚 comments about the satellite were from a speech at the North鈥檚 Academy of Defense Sciences, which he visited a day after a rocket carrying what would have been his country鈥檚 second military reconnaissance satellite exploded shortly after liftoff. North Korea鈥檚 aerospace technology administration said the explosion was possibly related to the reliability of a newly developed rocket engine that is fueled by petroleum and uses liquid oxygen as an oxidizer.

Animosities between the Koreas are at their worst level in years as the pace of both Kim鈥檚 weapons demonstrations and South Korea鈥檚 combined military exercises with the U.S. and Japan have intensified since 2022.

The failed satellite launch was a setback to Kim鈥檚 plan to launch in 2024 after North Korea鈥檚 was placed in orbit last November. The November launch followed two failed attempts.

Monday鈥檚 launch drew criticism from South Korea, Japan and the United States, because the United Nations bans North Korea from conducting any such rocket launches, viewing them as covers for .

North Korea has steadfastly maintained it has the right to launch satellites and test missiles in the face of what it perceives as U.S.-led military threats. Kim has described spy satellites as crucial for monitoring U.S. and South Korean military activities and enhancing the threat posed by his nuclear-capable missiles.

鈥淎lthough we failed to achieve the results we had hoped to get in the recent reconnaissance satellite launch, we must never feel scared or dispirited but make still greater efforts,鈥� Kim said. 鈥淚t is natural that one learns more and makes greater progress after experiencing failure.鈥�

North Korea hasn鈥檛 commented on when it would be ready to attempt a satellite launch again, which some experts say could take months.

State media鈥檚 mention of a liquid oxygen-petroleum rocket engine suggests the North is trying to develop a more powerful space launch vehicle that could handle larger payloads, according to some South Korean experts.

It is believed that North Korea鈥檚 previous space rockets used unsymmetrical dimethylhydrazine as fuel and dinitrogen tetroxide as an oxidizer. The country鈥檚 swift transition in space rocket designs possibly indicates external technological help, which would likely come from Russia, said Chang Young-keun, a missile expert at South Korea鈥檚 Research Institute for National Strategy.

Kim has been boosting the visibility of his ties with Russia in recent months, highlighted by a in September, as they align in the face of their separate confrontations with Washington. Kim鈥檚 meeting with Putin was held at a spaceport in the Russian Far East and came after North Korea鈥檚 consecutive failures in its attempts to launch its first spy satellite. Putin then told Russian reporters that Moscow was willing to help the North build satellites.

The U.S. and South Korea have also accused North Korea of providing Russia with artillery shells, missiles and other military equipment to help prolong its fighting in Ukraine.

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Kim Tong-hyung, The Associated Press