Russia's ambassador to the United States landed in Moscow on Sunday after being recalled for emergency consultations over the worst crisis in relations with the United States in years.
U.S. President Joe Biden on television earlier this week called the Russian leader a "killer" spurring a terse quip from Vladimir Putin who responded that, "it takes one to know one."
The exchange pushed diplomatic relations to a new low even after Moscow's ties with Washington were already at rock bottom over election meddling allegations and the Kremlin's decision to jail opposition figure Alexei Navalny.
Russia's envoy to the United States Anatoly Antonov landed at Moscow's Sheremetyevo Airport Sunday morning, Russian news agencies reported, after he was recalled last week over the spat.
Before takeoff in New York he told agencies he would stay in Moscow "as long as necessary" and that several meetings were scheduled.
"The Russian side has always stressed that we are interested in the development of Russian-American relations to the same extent as our American colleagues are," he was quoted as saying by TASS.
Moscow, which rarely returns ambassadors, last summoned its envoy in the U.S. in 1998 over a Western bombing campaign in Iraq.
In 2014, after the U.S. said Russia would face reprecussions for annexation of Crimea from Ukraine, Putin held back on recalling Moscow's envoy, describing the measure as a "last resort."