North Korean military briefly breached the demilitarised zone on Tuesday, South Korea reported, ahead of Russian President Vladimir Putin’s rare state visit to Pyongyang.
The soldiers retreated after the South Korean military fired warning shots, but Seoul believes the boundary infraction was unintentional.
South Korea said it suspected the soldiers entered accidently while strengthening the border, the second such event in over a week.
The boundary itself is not walled, and the signposts are covered by dense foliage.
South Korea’s Joint Chiefs of Staff (JCS) said about 20 to 30 soldiers came about 20 meters below the military demarcation line (MDL) inside the demilitarized zone (DMZ).
It is the second crossover incident in two weeks.
Seoul reports that North Korean troops entered into South Korea on June 9 with tools, including pickaxes. They fled when South Koreans responded with megaphone warnings and warning bullets.
According to the JCS, North Korea has been sending a huge number of personnel across the DMZ to remove vegetation and erect fortifications since April.
Military officials in Seoul stated that North Korean forces have suffered numerous casualties while operating near the DMZ due to landmine explosions during construction.
They added that North Korea completed restoring old guard posts in the area in January, before planting new landmines on roads between the countries.
The DMZ is one of the world’s most heavily fortified areas, a no-man’s land that stands as a remnant of the Cold War.
While 196 people fled North Korea to South Korea in 2023, almost none cross the fortified border. Most instead cross into China and then to South Korea.
The latest crossing comes as North Korea prepares to receive Russian President Vladimir for his first visit to the country in more than 20 years, after North Korean leader Kim Jong Un travelled to Russia last year.
The US has expressed concern about the deepening relationship between the two countries, saying it was troubled by the supply of North Korean missiles for the war in Ukraine.