The United States has pressed Russia and China to withdraw what he called their "intolerable" support for Venezuelan President Nicolas Maduro, as Washington steps up pressure on the Latin American leader to step down.
Addressing an international conference on Venezuela in Lima, Peru, on August 6, U.S. national-security adviser John Bolton called on Russia not to "double down on a bad bet."
Bolton also called on "all Cuban and Russian military and paramilitary forces to leave Venezuela immediately."
And he told China that "the quickest route to getting repaid" for its loans to Venezuela was by supporting "a new legitimate government."
The United States is one of more than 50 countries that do not recognize Maduro as Venezuela's legitimate president and are backing opposition leader Juan Guaido, who declared himself president in January.
Russia and China are Maduro's most powerful allies.
Moscow has admitted to sending military technicians to Venezuela as part of its defense cooperation with the South American country, but has denied deploying troops for military operations.
On August 5, President Donald Trump imposed sweeping sanctions on the Venezuelan government, freezing its assets in the United States and barring transactions with it.
"The time for dialogue is over. Now is the time for action," Bolton said. "We will ensure that Maduro runs out of ways to financially sustain himself."
Venezuela's Foreign Ministry denounced the fresh sanctions as "another serious aggression by the Trump administration through arbitrary economic terrorism against the Venezuelan people."
Russia's Foreign Ministry said Washington's restrictive measures were illegal and amounted to "economic terror," according to RIA Novosti news agency.
Maduro took office in 2013 and was sworn in for a second term in January following elections in May 2018 that were marred by an opposition boycott and claims of vote-rigging.
The opposition has also accused the socialist Maduro of mismanaging the economy, sending the country into an economic crisis. Maduro has blamed outsiders, including the United States, for creating the crisis.