CNN
 — 

North Korea sent a new wave of trash-laden balloons toward its southern neighbor late Sunday, after Kim Jong Un’s powerful sister warned of further responses if the South keeps up its “psychological warfare.”

The new balloons, which Seoul has previously slammed as “base and dangerous,” come in apparent retaliation for the decision by South Korea to resume broadcasting anti-North Korean propaganda over loudspeakers in border areas.

Kim’s sister and government spokeswoman Kim Yo Jong warned the resumption of loudspeaker broadcasts was “a prelude to a very dangerous situation.”

In a statement carried by North Korean state media, Kim said South Korea would be subject to an unspecified “new counteraction” from the North if it continued with the loudspeaker broadcasts and failed to prevent activists from sending anti-North Korean propaganda leaflets over the border.

“I sternly warn Seoul to stop at once this dangerous act,” Kim said, adding that Seoul is creating a “new environment of crisis.”

South Korea’s Joint Chiefs of Staff (JCS) has maintained North Korea is “fully responsible” for the current situation and urged the North to “immediately stop such mean acts like sending waste balloons.”

In a statement Monday, a JCS spokesman would not say whether the South would continue to broadcast over the loudspeakers, noting only that the military would conduct missions “with flexibility according to the strategic and operational situation.”

South Korea’s military once championed the propaganda broadcasts as part of psychological warfare against the North, until it withdrew the equipment following a 2018 summit between the neighbors.

The broadcasts inform North Korean soldiers and residents of the “reality of North Korea,” and the development of South Korea, and Korean culture, according to the JCS.

In recent weeks, the North has floated more than a thousand trash-filled balloons across the heavily fortified border, in what it claims is a response to the years-long practice among South Korean activist groups of sending balloons with anti-North Korea leaflets in the other direction.

As of Monday morning, the South Korean military has found “around 50 balloons” that fell into its territory overnight Sunday. Many of the other balloons are believed to have flown back into North Korea due to the wind, the JCS spokesman added.

The escalating tit-for-tat has sparked concerns of potential retaliatory military action. Last week, the South Korean government suspended a 2018 deal to reduce military tensions with the North, allowing it to resume propaganda broadcasts and potentially restart military exercises along the border.

Last week, South Korean activists sent balloons across the border toward the North carrying hundreds of thousands of leaflets condemning leader Kim Jong Un and 5,000 USB sticks containing K-pop and K-dramas.

For decades, North Korea has been almost completely closed off from the rest of the world, with tight control over what information gets in or out. Foreign materials including movies and books are banned, with only a few state-sanctioned exceptions; those caught with foreign contraband often face severe punishment, defectors say.

Earlier this year a South Korean research group released rare footage that it claimed showed North Korean teenagers sentenced to hard labor for watching and distributing K-dramas.

Restrictions softened somewhat in recent decades as North Korea’s relationship with China expanded. Tentative steps to open up allowed some South Korean elements, including parts of its pop culture, to seep into the hermit nation – especially in 2017 and 2018, when relations thawed between the two countries.

But the situation in North Korea deteriorated in the following years and diplomatic talks fell apart – prompting strict rules to snap back into place in the North.