Seoul says South Korea has begun clearing mines from two sites inside the heavily fortified border with North Korea under a package of tension-reduction deal between the rivals.
Seoul's Defense Ministry says North Korea is expected to do the same on Monday.
Ministry officials say South Korean troops entered the Demilitarized Zone on Monday morning to remove mines around the border village of Panmunjom and another frontline area where they plan their first joint searches with North Korea for soldiers during the 1950-53 Korean War.
The Koreas' militaries agreed on a range of deals aimed at lowering their decades-long military animosities on the sidelines of a summit between their leaders in Pyongyang.
The move comes amid renewed international diplomacy on North Korea's nuclear program.