The EU and US have announced travel bans and assets freezes against a number of officials from Russia and Ukraine.
The move follows Sunday’s referendum in Crimea in which officials say 97 percent of voters backed breaking away from Ukraine and joining Russia.
The individuals targeted by the sanctions are seen as having played a key role in the referendum which Kiev, the US and EU deem illegal.
Pro-Russian forces have been in control of Crimea since February.
Moscow says the troops are Pro-Russian self-defence forces and not under its direct control.
The crisis follows the custing on 22 February of Ukraine’s Pro-Moscow President Victor Yanukovych, who had sparked months of street protests by rejecting a planned EU trade deal in favour of closer ties with Moscow.