In total, between 1965 and 1973, 312,853 South Korean soldiers fought in Vietnam; Vietnam's Ministry of Culture and Communications in an unofficial investigation[6] estimated they killed 41,400 enemy fighters and 5,000 civilians.[7] After the Vietnam war, there were thousands of children of mixed Korean and Vietnamese descent, called Lai Dai Han, born of Korean workers or soldiers and local Vietnamese.[8] Reportedly, many resulted from widespread "My Lai-style massacres" that[9] involved the rape of Vietnamese Women by South Korean soldiers.[8] Various civil society groups continue to hope for a formal investigation and apology into these events.[10]
South Korean (ROK) soldiers were heavily involved in the US-Vietnam war and had a reputation for being effective but brutal. Maybe this is related to that?