Anchor: North Korean soldiers crossed the inter-Korean border briefly on Sunday and retreated after South Korea fired warning shots. According to the South Korean military on Tuesday, a group of North Korean troops violated the border in the Demilitarized Zone(DMZ) on Sunday just hours before South Korea resumed its loudspeaker broadcasts towards the North. 
Kim Bum-soo has more.
 
Report: South Korean soldiers fired warning shots after North Korean troops violated the inter-Korean border in the heavily fortified Demilitarized Zone earlier this week.
 
The South Korean Joint Chiefs of Staff(JCS) on Tuesday revealed the incursion that occurred on Sunday.
 
[Sound bite: JCS Spokesman Col. Lee Sung Joon (Korean-English)]
"At about 12:30 p.m. on June 9, a group of North Korean soldiers crossed the Military Demarcation Line(MDL) within the Demilitarized Zone. They crossed back to the North after our military issued warning broadcasts and fired warning shots.”
 
JCS spokesman Col. Lee Sung Joon said that there were no suspicious activities by the North Korean soldiers, who the South Korean military believes did not intend to cross the line. 

He explained that the DMZ is thick with bushes, making the military demarcation line difficult to see. 
 
The trespassing came, however, amid intensified tensions over the North’s release of trash balloons, which the South Korean military countered on Sunday by reactivating loudspeaker psychological warfare operations near the DMZ.
 
[Sound bite: JCS Spokesman Col. Lee Sung Joon (Korean-English)]
"North Korea installed anti-South Korea loudspeakers, and they were surely installed to start anti-South Korea propaganda broadcasts. Such propaganda broadcasts have not been heard yet."

The incursion took place just hours before South Korea's resumption of loudspeaker broadcasts.

The South Korean military said that it is taking necessary measures in accordance with standard operating procedures, while closely monitoring the movements of the North Korean troops.​
Kim Bum-soo, KBS World Radio News.