The development comes amid renewed international diplomacy on North Korea's nuclear weapons program after weeks of stalemated negotiations. U.S. Secretary of State Mike Pompeo is to visit Pyongyang this month to try to set up a second summit between President Donald Trump and North Korean leader Kim Jong Un.
South Korean troops entered the Demilitarized Zone on Monday morning to remove mines around the border village of Panmunjom and another frontline area where the rivals plan their first joint searches with North Korea for soldiers during the 1950-53 Korean War, according to Seoul's Defense Ministry.
The South Korean troops will try to focus on taking out mines on the southern parts of Panmunjom's Joint Security Area and the so-called "Arrow Head Hill," where one of the fiercest battles during the Korean War happened. Seoul officials believe the remains of about 300 South Korean and U.N. forces are in the Arrow Head Hill and likely many Chinese and North Korean remains too.
South Korean Defense Ministry officials said they couldn't immediately confirm whether North Korea also began demining on the northern parts of the two sites. But they said they expected the North to abide by the tension-easing deals their defense chiefs struck on the sidelines of their leaders' summit last month in Pyongyang.
Aiming to reduce conventional military threats, the Koreas' defense chiefs also agreed to withdraw 11 frontline guard posts by December and set up buffer zones along their land and sea boundaries and a no-fly zone above the borderline to prevent accidental armed clashes.
About 2 million mines are believed to be peppered inside the Koreas' 248-kilometer (155-mile)-long Demilitarized Zone that was originally created as a buffer zone at the end of the Korean War. The DMZ is the world's most heavily fortified border that is also guarded by hundreds of thousands of combat troops, barbed wire fences and tank traps on both sides.
Many experts say the fate of inter-Korean deals can be affected by how nuclear negotiations would go between the United States and North Korea. Past rapprochement efforts were often stalled after an international standoff over the North's nuclear ambitions intensified.
After provocative tests of three intercontinental ballistic missiles and a powerful nuclear weapon last year, North Korea entered talks with the United States and South Korea earlier this year, saying it's willing to deal away its expanding nuclear arsenal. Kim Jong Un has subsequently held a series of summits with U.S., South Korean and Chinese leaders and taken some steps like dismantling his nuclear-testing site.
Nuclear diplomacy later came to a standstill amid disputes over how genuine North Korea is about its disarmament pledge. But Trump, Pompeo and other U.S. officials have recently reported progress in the denuclearization discussions with the North. Pompeo is to make his third trip to North Korea soon for talks.