Russia had sent two planes reportedly carrying around 100 soldiers and 35 tons of military equipment to Venezuela's main airport outside Caracas on Saturday.
Russia's foreign ministry said Tuesday that Moscow's decision to send military specialists to Caracas was in full accordance with Venezuelan law, after Russian military planes delivered troops and equipment to the country in a move denounced by Washington.
Russian foreign ministry spokeswoman Maria Zakharova said in a statement that Moscow is "developing cooperation with Venezuela in strict accordance with the constitution of that country and with full respect for its legal norms."
She added that "the presence of Russian specialists on Venezuelan territory is regulated by an agreement between the Russian and Venezuelan governments on military and technical cooperation that was signed in May 2001."
US Secretary of State Mike Pompeo had warned his counterpart Sergei Lavrov over the phone that "the United States and regional countries will not stand idly by as Russia exacerbates tensions in Venezuela."
The tense conversation came after Russia sent two planes reportedly carrying around 100 soldiers and 35 tons of military equipment to Venezuela's main airport outside Caracas on Saturday.
Although Russian state news agency Sputnik described the troop arrival as a movement to "fulfill technical military contracts," the development unsettled Washington, which has thrown its weight behind opposition leader Juan Guaido as interim president against President Nicolas Maduro.
"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 who overwhelmingly support interim President Juan Guaido," Pompeo said, according to his office.
The Organization of American States echoed the US condemnation.
Lavrov said in a statement he had complained of "attempts by Washington to organize a coup d'etat in Venezuela" during his conversation with Pompeo.
Such moves "constitute violations of the UN charter and undisguised interference in the internal affairs of a sovereign state," it said.