The standoff has increased tensions between the United States and Russia, who accused each other of interference in Venezuela's affairs.

Venezuela's opposition leader Juan Guaido on Wednesday called for the military to support him and the "largest march" in the country's history. But the armed forces has remained loyalty to Maduro's government. And by late afternoon, many of the protesters in the capital Caracas were drifting home.  

The fault lines are increasingly putting Venezuela at the heart of global geopolitical tensions.

The U.S. government has been pressing Maduro to force him out of power with sanctions.

On Wednesday, President Donald Trump's secretary of state said military intervention is still possible.

"Military action is possible. If that's what's required, that's what the United States will do," Mike Pompeo told Fox Business Network.

The Pentagon appeared to downplay any ongoing preparations to intervene in Venezuela directly but acknowledged detailed contingency planning.

On Tuesday, Pompeo said Maduro was ready to flee to Cuba but was dissuaded by Russia. Russia's Foreign Ministry rejected the claim, calling it part of an "information war."

On Wednesday, Russian Foreign Minister Sergei Lavrov spoke to Pompeo on the phone. Lavrov said further "aggressive steps" in Venezuela would have grave consequences.

On the same day, the White House National Security Council held a meeting on the next steps facing the political turmoil in Venezuela.

After the meeting, National Security Advisor John Bolton told reporters Moscow's involvement was not welcome.

"This is our hemisphere," he said. "It's not where the Russians ought to be interfering. This is a mistake on their part. It's not going to lead to an improvement of relations."

Speaking in a televised broadcast on Tuesday, Maduro said his government has defeated the attempted coup after Guaido called for a military uprising.

Maduro also called a march of his own supporters on Wednesday. "We have been confronting different types of aggression and attempted coups never before seen in our history," he said on Tuesday.  Several thousand Maduro supporters, wearing red shirts, headed toward the Miraflores presidential palace.

(With inputs from Reuters)

(Cover: An opposition supporter runs with a tear gas canister during a rally against the government of Venezuela's President Nicolas Maduro and to commemorate May Day in Caracas Venezuela, May 1, 2019. /Reuters Photo)