A Russian law that criminalizes undeclared dual citizenship for Russian citizens has come into force.
The law was adopted by the State Duma in May and signed by President Vladimir Putin in July.
It imposes a fine of up about $5,800 or 400 hours of community service on Russians who fail to inform the Russian authorities that they have obtained citizenship in another country.
For residents of Crimea -- the Ukrainian region that was annexed by Russia in March -- Russian authorities will begin enforcing the law on January 1, 2015.
The procedure necessary for declaring dual citizenship remains unclear.
Human rights activists in Russia have criticized the law.
They say it puts people with dual citizenship "under suspicion" and exposes them to pressure from Russian authorities.