SEOUL, South Korea--South Korea said Sunday it was bolstering its anti-Pyongyang propaganda broadcasts across the tense border with rival North Korea, after the North launched more balloons likely carrying trash toward South Korea.

The Cold War-style psychological battle between the two Koreas is adding to already-high tensions on the Korean Peninsula, with the rivals threatening stronger steps against each other and warning of devastating consequences.

South Korea’s Joint Chiefs of Staff said the North Korean balloons were flying Sunday morning north of Seoul, the South Korean capital, after crossing the border. It said later Sunday that the South Korean military was responding by expanding loudspeaker broadcasts at all major sections of the Koreas' 248-kilometer (154-mile)- long border.

“The North Korean military’s tension-escalating acts can result in causing critical consequences for it,” the South Korean Joint Chiefs of Staff said in a statement. “The responsibility for this kind of situation is entirely on North Korea’s government.”

Details of the expansion of South Korea's loudspeaker operations were not immediately available. On Thursday, it resumed blasting frontline propaganda broadcasts for the first time in about 40 days in response to the North's previous balloon activities. But observers say South Korea hadn't been conducting the broadcasts around the clock and it also hadn't yet mobilized all of its loudspeakers.

The latest South Korean broadcasts included K-pop songs and news on BTS member Jin’s torch-bearing ahead of the Paris Olympics and the recent defection of a senior North Korean diplomat. The broadcasts also called the mine-planting works by North Korean soldiers at the border “hellish, slave-like lives,” according to South Korean media.

Experts say South Korean propaganda broadcasts can demoralize frontline North Korean troops and residents, posing a blow to the North's efforts to limit access to outside news for its 26 million people. South Korean officials have previously said broadcasts from their loudspeakers can travel about 10 kilometers (6 miles) during the day and 24 kilometers (15 miles) at night.

North Korea hasn't made an official response to the ongoing South Korean broadcasts. But in 2015, North Korea fired artillery rounds across the border in response to South Korea's first loudspeaker broadcasts in 11 years, prompting the South to return fire, according to South Korean officials. No casualties were reported.

North Korea’s latest balloon-flying on Sunday is the ninth of its kind since late May. North Korea has floated more than 2,000 balloons to drop waste paper, scraps of cloth, cigarette butts, waste batteries and even manure on South Korea, though they have so far caused no major damage in South Korea. North Korea has said the initial balloons were launched in response to South Korean activists sending political leaflets to the North via their own balloons.

Like South Korean frontline broadcasts, North Korea views the South's civilian leafleting activities as a major threat to its authoritarian government led by Kim Jong Un. In furious responses to past South Korean leafletting, North Korea in 2020 destroyed an empty South Korean-built liaison office in its territory and in 2014 it fired at incoming balloons.

In a statement last week, Kim's powerful younger sister, Kim Yo Jong, warned that South Korean “scum” must be ready to pay “a gruesome and dear price" over the leafleting activities. She said more South Korean leaflets had been found in North Korea.

That raised concerns North Korea could stage physical provocations, rather than balloon launches. South Korea's military said North Korea may fire at balloons or scatter mines downriver.

In early June, South Korea suspended a 2018 tension-reduction deal with North Korea, a step required for it to restart propaganda broadcasts and conduct live-fire military drills at border areas in response to the North's balloon campaigns.

On June 9, South Korea made propaganda broadcasts for about two hours but had not done them again to avoid raising animosities until Thursday. South Korea warned Friday it would conduct loudspeaker broadcasts in a fuller manner and take other stronger steps if North Korea continues provocations like balloon launches.

Tensions on the Korean Peninsula have already been running high because of North Korea's provocative run of missile tests and the expansion of U.S.-South Korean military drills that North Korea calls invasion rehearsals. Experts say North Korea’s expanding ties with Russia could embolden Kim Jong Un to stage bigger provocations.