On Monday, the Russian Foreign Ministry summoned the US ambassador to Moscow, John Sullivan, over President Joe Biden's comments about his counterpart Vladimir Putin, describing him as a war criminal.
"Such statements by the American president, which are not befitting a statesman of such high stature, put relations between Russia and America on the verge of collapse," the Russian ministry said in a statement.
The ministry assured Sullivan that hostile actions against Russia would receive a "decisive and resolute response."
The Kremlin earlier described the comments as "personal insults" to Putin.
And last Wednesday evening, the US President announced his belief that Putin is a war criminal, because of his country's military operation against Ukraine.
Biden's comments came a day after the US Senate passed a draft resolution seeking to support the investigation into the Russian President's war crimes in the military operation in Ukraine.
Russia sent tens of thousands of troops to Ukraine on February 24, in what it described as a special operation to destroy the military capabilities of its southern neighbor and eliminate what it describes as "dangerous nationalists."
In response to that military operation, the West imposed broad sanctions on Moscow as part of efforts to force it to withdraw, and announced billions of dollars in military aid to Ukraine.