GOSEONG, South Korea — With Memorial Day approaching in the United States, which lost 36,516 troops in the Korean War, a convoy of South Korean K1 tanks lumbers up the east coast highway toward the southern side of the demilitarized zone dividing North from South Korea. Inside the zone, at the northernmost observation point facing distant North Korean guard posts, an officer from the South’s 22^nd division talks about our common foe.