Between 20 to 30 North Korean soldiers entered South Korean territory today (Tuesday).
In response, South Korean soldiers opened fire with warning shots, causing the North Korean soldiers to return back to their country.
A similar event occurred earlier this month, which also ended with warning shots.
The events are occurring while North Korean soldiers are working around the demilitarized zone, clearing mines and paving roads, following an order from the dictator Kim Jong-un in March to prepare "intensively" for war.
Such events could lead to a deterioration in relations between the countries, which are already in a particularly tense state.
Last week, South Korea announced that it had decided to resume broadcasts against North Korea using the powerful loudspeakers in its possession.
The broadcasts using the loudspeakers were stopped in 2018 during a period of calm relations between the countries after the loudspeakers were placed near the border and high-volume messages against the totalitarian regime were broadcast from them.
Seoul's decision to resume the broadcasts comes after weeks during which Pyongyang sent over 1,000 garbage balloons containing trash, feces, and paper waste across the border.