On Monday, the U.S. accused Russia of aggravating political tensions in Venezuela. That prompted the Kremlin to repeat its claim that the White House has been trying to orchestrate a "coup."
It comes less than 48 hours after two Russian military planes touched down in Caracas, fueling speculation that Moscow is seeking to bolster its presence in the oil-rich, but cash-poor, country.
U.S. Secretary of State Mike Pompeo discussed the escalating crisis in Venezuela with his Russian counterpart Sergei Lavrov via telephone on Monday.
"(The U.S.) will not stand idly by as Russia exacerbates tensions in Venezuela," Pompeo said, according to a statement released by the State Department on Monday.
"The continued insertion of Russian military personnel to support the illegitimate regime of Nicolas Maduro in Venezuela risks prolonging the suffering of the Venezuelan people," Pompeo said, criticizing Moscow's "unconstructive behavior."
In response, Russia's Lavrov said: "Washington's attempts to stage a coup in Venezuela and threats against its legitimate government were a violation of the UN Charter and blatant interference in the internal affairs of a sovereign state," according to a statement by the foreign ministry on Monday.