What countries are not supported by Coinbase?

I'm interested in exploring the global reach of Coinbase, a popular cryptocurrency exchange. Could you please elaborate on which countries are currently unsupported by the platform? Are there any specific regions or jurisdictions that Coinbase has chosen not to operate in due to regulatory constraints, legal issues, or other factors? Understanding these limitations would be invaluable for me as I evaluate the suitability of Coinbase for my international cryptocurrency transactions.