Venezuela's President Nicolás Maduro says he has foiled an ‘attempted coup’ by opposition leader Juan Guaidó.
Dozens of National Guardsmen sided with the opposition in clashes on Tuesday that injured more than 100 people.
But in a defiant TV address, President Maduro said Mr Guaidó had failed to turn the military against him.
Mr Guaidó insists that Mr Maduro has lost control of the armed forces. The opposition leader called for more streets protests on Wednesday.
"Today we continue," he tweeted. "We will keep going with more strength than ever, Venezuela."
Mr Guaidó has been recognised as interim leader of Venezuela by more than 50 countries, including the US, the UK and most in Latin America.
The US reiterated its support for Mr Guaidó on Wednesday, with Secretary of State Mike Pompeo saying "military action is possible" if necessary.
But Mr Maduro, backed by Russia, China and the top of the country's military, has refused to cede leadership to his rival.
Mr Pompeo was scheduled to speak with Russia's Foreign Minister Sergei Lavrov on Wednesday, National Security Adviser John Bolton said.
In his televised address, flanked by military commanders, Mr Maduro accused protesters of ‘serious crimes’ which he said would not go unpunished.
Both the president and Mr Guaidó have called on their supporters to take to the streets, setting up more potential violent unrest in a nation already beset by economic crisis, chronic power cuts and widespread food shortages.