I am aware of the debate between whether Taiwan is a province of China vs whether Taiwan and China are 2 separate countries.
For that issue, China's official name is People's Republic of China and Taiwan's official name is Republic of China, so some argue that this suggests there is 1 China, and that both regions are part of it.
Also for that issue, Taiwan has not officially declared independence, and some argue that this is further evidence for why Taiwan is not a country, and is therefore a province of China.
So even though China and Taiwan each have their own clearly-defined land, military, and national identity, these are 2 major arguments that there is only 1 China, and that Taiwan is a province of China.
Well, these 2 points seem to apply equally to the Korea situation.
Firstly, North Korea's official name is Democratic People's Republic of Korea, while South Korea's official name is Republic of Korea. This seems to suggest that there is 1 Korea and that these 2 regions are part of it.
Secondly, neither North Korea nor South Korea have declared independence. The Korean national holiday of Independence Day falls on the same day (August 15th) for both North and South Korea, because independence was declared from Japan before Korea split into North and South Korea.
Therefore, it seems that it can be argued that there is only 1 Korea, as much as there is only 1 China.
So is there only 1 Korea? And is South Korea a province of Korea?