Which countries are unsupported by Coinbase?

Could you please provide me with a list of countries that are not supported by Coinbase? I'm interested in understanding the geographical limitations of this cryptocurrency platform and want to ensure that I'm aware of any potential restrictions in my region. Additionally, it would be helpful if you could explain any reasons why these countries might be unsupported, such as regulatory issues or other factors. Thank you for your assistance in clarifying this matter.