"This is the result of colossal pressure, colossal blackmail which is the main instrument of Washington on the international arena," Russian Foreign Minister Sergei Lavrov said in Uzbekistan, AFP reported.
"We'll respond, have no doubt! No one wants to put up with such loutish behavior and we won't."
The United States said on Monday it would expel 60 Russian diplomats, joining governments across Europe in punishing the Kremlin in response to a nerve agent attack on a former Russian spy in Britain that the British government has blamed on Moscow.
In total, 100 Russian diplomats were being removed, the biggest Western expulsion of Russian diplomats since the height of the Cold War.