South Korean soldiers fire warning shots after troops briefly cross border from North

South Korean soldiers fired warning shots after North Korean soldiers accidentally crossed the border, South Korea’s military said.

Some North Korean troops engaged in unspecified work on the border crossed the demilitarized zone line that separates the two countries, The Associated Press reported.

The soldiers were carrying construction tools and some of them were armed. They immediately returned to their side after South Korea fired warning shots and issued warning broadcasts, according to South Korea’s Joint Chiefs of Staff.

The south said the soldiers didn’t appear to intentionally cross the border because the area was heavily wooded and signs were not visible.

Local media reported that 20 to 30 North Korean soldiers entered about 165 feet.

The AP noted that the 155 mile long “Demilitarized Zone,” or DMZ, is the world’s most heavily armed border.

The warning shots follow back-and-forth provocations between the two countries.

North Korea continued its mission of sending balloons filled with trash to the south last week. The balloons contain “filth” like cigarette butts, waste paper and plastic bags.

South Korea pledged its response would be “unbearable.” South Korea began playing Korean pop music on its loud speakers and anti-Pyongyang propaganda in retaliation for the trash balloons, The AP reported.

North Korean leader Kim Jong Un’s sister, Kim Yo Jong, said Sunday that a “new response” would be coming if the south continued its loudspeaker broadcasts, the outlet reported.

The Associated Press contributed.