Russia's Foreign Ministry said it expelled two U.S. diplomats from Moscow in June in response to what it called a similar "unfriendly" move by Washington, amid an escalating diplomatic dispute between the two countries.
One of the expelled diplomats was involved in an incident with a Russian guard near the U.S. Embassy entrance in Moscow, the Foreign Ministry said in a statement, citing Deputy Foreign Minister Sergei Ryabkov.
Another diplomat was "also a CIA operative," Ryabkov said.
The statement came one day after the United States announced it expelled two Russian officials following the violent altercation last month outside the U.S. Embassy in Moscow.
U.S. State Department spokesman John Kirby said the Russians were thrown out on June 17 in connection with the incident that occurred earlier in the month in the Russian capital, but gave no further details.
It wasn't immediately clear who the Russians were and whether they were accredited diplomats.
The altercation in Moscow occurred June 6, when a man identified as an accredited U.S. diplomat was tackled and injured by a Russian security service guard outside an embassy entrance.
U.S. officials said the American had just shown his embassy badge to the guard, one of several that help monitor the perimeter of the massive embassy complex and who work for the Federal Security Service, the country's main security agency.
The guard then tackled the diplomat, leaving him with a broken shoulder.
Russia later accused the man of being a CIA agent.
The incident came amid an increasing number of tense encounters between U.S. diplomats and Russian security officials in Moscow and elsewhere.
Moscow traffic police have stopped U.S. embassy personnel about five dozen times over the six weeks, according to the U.S. official -- an unusual number in a city where diplomats are usually afforded leeway for things like minor traffic violations.
And the spokesman for the U.S. diplomatic post last week reported returning home to find cigarettes in his apartment; another reportedly returned home to find the water taps turned on.
Secretary of State John Kerry discussed the incident with Russian Foreign Minister Sergei Lavrov in a phone call on June 7, the day after the altercation, Kirby told reporters July 7.
In Washington, American officials have given few details publicly about any of the incidents, but stressed on several occasions that they wanted to resolve the harassment behind closed doors and without publicity.