When studying international law, I learnt that a "nation-state" (in layman terms: a country) needs to have the following:

  1. A defined territory.
  2. A permanent population.
  3. A government.
  4. The capacity to enter into relations with other states.

In practice, there is one more requirement, which is perhaps the most important of all:

  5. Recognition by other nation-states.

In other words: a cargo ship does not a country make.

Reference: https://www.open.edu/openlearn/society-politics-law/explorin...