country
國 centers on a bounded territory: a country or nation. The meaning is straightforward and singular.
國 combines 囗 (enclosure, boundary) with 或, which likely contributed the sound and the idea of a territory. The character represents a defined region or country.
The outer 囗 is a border wall, and inside is 或, which looks like a guarded territory with a weapon 戈. Picture a walled city-state: 國 is a country.
For コク, imagine a country shaped like a giant coke bottle: coke -> コク, and the border 囗 contains the fizzy nation inside.