Russia's Federal Security Service (FSB) has established a security zone with border controls along the country's border with neighboring Belarus.
A set of government documents posted on February 1 said a "full-fledged border-protection regime" has been established after Belarus last month announced it was abolishing visas for short-term visitors from some 80 countries, including the United States and European Union member countries.
The new visa policy takes effect on February 9.
Russia's decision came as a surprise because Russia and Belarus have formed a "union state" since January 2000 and there have been no border controls between the two countries.
However, officials in Moscow have said Minsk's decision to abolish visas presents a security threat to Russia.
Belarusian television said the government was not commenting on the new security zone.
With reporting by TASS and Interfax