Divided at the 17th parallel in 54/55.
The Geneva Accords divided Korea in 1954
All areas outside of the Communist countries. South of the 38th Parallel in Korea. South of the 17th Parallel in Vietnam. West of the East/West German line, etc.
The 17th parallel is the line of latitude 17 degrees North of the Equator. I'm not sure of any particular significance to WWII directly; it was where Vietnam was divided into North and South (in the mid-1950s) though, which might be what you're thinking of.
When the Geneva Accords divided up the country following the end of the French Indochina War in 1954/55, the communists took the lands north of the 17th Parallel, and the free world occupied the country south of the 17th Parallel; the US was involved immediately at that time.
17th Parallel
It followed the 17th parallel of latitude on the map.
Vietnam was split at the 17th parallel
17th parallel.
A parallel.
Latitude
17th Parallel.
IDE
parallel
Parallel
parallel
parallel?