Thousands of milky latex balloons from North Korea have glided toward its southern neighbor since May, many of them crossing the Demilitarized Zone, the world’s most heavily armed border, with unusual payloads: scraps of used paper and other common trash.

Some have pierced another layer of security and landed in the compound that houses the South Korean president’s office.

Other balloons have floated from South Korea into the North, ferrying leaflets, USB sticks and other items that Pyongyang considers political “filth.”

Propaganda has been flying across the border since the Korean War in the early 1950s. But flinging garbage, including cigarette butts and compost, is a new twist from North Korea that could escalate hostilities at a time when dialogue between the two nations is at a standstill.

Here’s what we know about the latest balloon battles.

The balloons started drifting over as North Korean defectors and other activists living in South Korea launched hundreds of plastic inflatables to deliver propaganda, or thought bombs. North Korea responded with more than 3,000 trash balloons.

The Times had access to cargo packed by two Seoul-based activist groups. A typical balloon launched by one of them, the Committee for Reforming and Opening North Korea, carries a dispenser that spits out 25 leaflets every five minutes once it reaches an altitude of two to three miles.

These leaflets exhort North Koreans to “rise up” against the dictatorship of Kim Jong-un, the country’s leader.

Other leaflets describe Mr. Kim’s complex family tree, which shows the multiple wives of his father and grandfather when they were ruling the country. Such information remains off-limits to North Koreans.

Another type of balloon from South Korea releases colorful parachutes that are equipped with small battery-powered loudspeakers.

Upon impact, they start blaring recordings in the strident tone of a typical North Korean newscaster. One of the messages says, “North Korea can live when its Workers’ Party dies!”

Some South Korean balloons are also outfitted with an altimeter to calibrate the payload drop.

Its control device, built with cheap Chinese components, releases hydrogen from the balloon to prevent it from going up too high, or dumps some leaflets to stop the balloon from dropping too low too soon.

North Korea allows no press freedom or religion. All radio and TV sets are pre-fixed to receive only government broadcasts, which praise Mr. Kim’s godlike status and instill in North Koreans a hatred and fear of the United States.

Airdrops of abridged versions of the Bible and short-wave radio sets, which allow North Koreans to access outside news, are aimed at chipping away at the totalitarian information blackout and his cult of personality.

Information blitzes also happen through lightweight flash drives that are packed with K-pop and K-dramas that Mr. Kim has called a “vicious cancer.” They also include documentaries about the Kim regime and the demise of foreign dictators, including Nicolae Ceausescu and Muammar el-Qaddafi.

The activist group Fighters for Free North Korea said that during its latest launch, it sent 20 balloons carrying 5,000 USB sticks.

North Korea’s trash balloons have provided clues to life in the isolated North, South Korean officials said.

The cargo has included patched-up socks and discarded clothes, some with images of Mickey Mouse and Hello Kitty, despite Pyongyang’s tirade against outside influence.

Some of the contents included compost that contained roundworms and other human parasites — a sign that North Koreans used human waste for fertilizer.

Some South Koreans called North Korean inflatables “poop balloons.”

When the first batch of North Korean balloons arrived, the South Korean government urged people not to touch them.

Pyongyang is known to hold large stockpiles of biological and chemical weapons. South Korean soldiers, donning full protective gear, were deployed to inspect the payloads.

Activists in South Korea vowed to send as many balloons as their funding allowed.

But North Korea has one great advantage in the balloon war: On the Korean Peninsula, the winds more often blow to the south than to the north.