Peace is preserved by hiding the truth

A forbidden friendship between four South and North Korean border guards. A completely absurd risk of getting caught. If it were to be revealed, the impact could be world-changing. Eliminating them would probably be the simplest option to keep their mouths shut for good. But first they have to be exposed. Joint Security Area (2000) is a little confusing at first because the story unfolds mostly through flashbacks, and very slowly, but fortunately it's rewarding in the end.