Russian Deputy Foreign Minister Sergei Ryabkov has said Moscow is able to take "asymmetrical" and "painful" measures if the United States imposes tougher sanctions on the country.
Ryabkov was addressing lawmakers in the lower house of parliament -- the State Duma -- who later approved President Vladimir Putin's decree on suspending a plutonium disposal agreement with Washington.
INFOGRAPHIC: What Is The U.S.-Russia Plutonium Agreement?
In the bill submitted to parliament on October 3, Putin sets pre-conditions for the accord to be resumed -- including lifting all U.S. sanctions against Russia and compensation for the damage they have caused, and reducing U.S. military infrastructure and troops in Eastern Europe.
On October 16, the United States and Britain said they were considering new sanctions to pressure the Syrian government and its supporters to end the bombardment of the city of Aleppo.
Russia has been a key ally of Syrian President Bashar al-Assad.