[1] Before 1973, OPLAN 5027 was primarily focused on defeating a North Korean invasion, with a 50-mile retreat from the penetrated Demilitarized Zone to positions south of the Han River (known as the Hollingsworth Line).
No mention was made of the use of tactical nuclear weapons in case of overwhelming North Korean forces, though the Congressional Budget Office predicted that without their use, the new strategy could result in the initial loss of Seoul.
Further revisions and more detailed offensive strategies were incorporated in late 1998 into OPLAN 5027-98, with new focus on countering sudden chemical and biological attacks against Seoul.
Most known versions of OPLAN 5027 assume a surprise attack by North Korea, with the initial intent of destroying allied defenses and gaining a significant foothold before the rallying of South Korean forces or American reinforcements.
North Korea would presumably try to leverage its quantitative advantage of troop strength against the perceived superior technological capabilities of South Korean and US forces.