Yes, but normally if you are blocking a country you want to block "from and to" to drop both connections initiated from that country, and any "phone home" attempts to that country initiated by malware already inside your network. Also ensure that "Default Geo Policy" is applied to your firewall on the Gateways screen.
As Phoneboy says though use of Geo Updatable Objects in the mainline Access Control policy in R80.20+ is much more flexible and easy to work with.
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