In the first major action by the government of Venezuelan President Nicolás Maduro to fend off a leadership challenge, the country's Supreme Court on Tuesday barred opposition leader Juan Guaidó from leaving Venezuela and ordered a freeze on his financial assets.

Chief Justice Maikel Moreno said the court was initiating a "preliminary investigation" into Guaidó and taking "precautionary measures" against the U.S.-backed opposition leader to "safeguard the country's integrity." In the spring of 2017, Moreno sparked controversy in Venezuela and around the world when he nullified the powers of the National Assembly after opposition lawmakers gained control of the body through an election.

The decision by the 32-member tribunal came after Venezuela's attorney general Tarek Saab asked the court, which is stacked with Maduro's allies, to launch a criminal probe against Guaidó, the 35-year-old president of the country's National Assembly. During a press conference outside the court Tuesday, Saab accused Guaidó of leading an "assault against the Venezuelan fatherland," but did not mention any specific crimes he believed the opposition leader had committed.

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Responding to Saab's announcement at a press conference before the court's order, Guaidó said he did not underestimate the threat of imprisonment, but he did not believe it was "anything new." He added the accusations were part of the Maduro regime's pattern of persecution and repression against the Venezuelan people.

The Trump administration — which, along with more than a dozen other governments, has pledged its support for Guaidó — quickly condemned the action by Venezuela's chief prosecutor and vowed that any harm to the opposition leader would provoke "serious consequences."

"We denounce the illegitimate former Venezuelan Attorney General's threats against President Juan Guaido. Let me reiterate - there will be serious consequences for those who attempt to subvert democracy and harm Guaido," national security adviser John Bolton tweeted Tuesday, echoing a similar warning he issued on Sunday.

Since it recognized Guaidó as Venezuela's legitimate interim president, the Trump administration has escalated its efforts to isolate Maduro's authoritarian government.

On Tuesday, Vice President Michael Pence met with Carlos Alfredo Vecchio, who the Trump administration has recognized as Venezuela's Chargé d'Affaires in Washington. After the meeting, Vecchio said Guaidó could be arrested by Venezuelan authorities. "This is a fight between democracy and dictatorship" he told reporters.

Vecchio added there's a "unique opportunity" for a transition of power to occur in Venezuela. "We have a legitimate president. An illegitimate dictatorship. We have the momentum. We have the people. We have a united opposition. We have a strong national assembly. And we have the democratic world backing us, supporting our agenda," he said.

Earlier in the day, the State Department announced it had granted Guaidó control over some of the Venezuelan government's bank accounts held by U.S.-insured banks. On Monday, Bolton and Treasury Secretary Steven Mnuchin unveiled sweeping sanctions against Venezuela's state-owned oil company, Petróleos de Venezuela, S.A., or PdVSA. During the announcement at the White House, Bolton held a legal pad with the words "5,000 troops to Colombia" written on it.

Asked for comment on the note, a White House spokesperson told CBS News, "As the president has said, all options are on the table." Colombia's Foreign Minister Carlos Holmes said his government was not aware of the "importance and reason" for Bolton's note.

Guaidó's declaration last week set off a new wave of violence and chaos in oil-rich Venezuela — once considered one of Latin America's wealthiest countries. A United Nations spokesperson said Tuesday more than 40 people have been killed during the recent massive protests in the South American nation.

In recent years, plummeting oil production, skyrocketing inflation and mismanagement have devastated the Venezuelan economy and led to widespread food shortages. The dire situation has prompted more than 2.3 million Venezuelans to flee the country since 2014 — an exodus Human Rights Watch called "the largest migration crisis of its kind in recent Latin American history."

Guaidó is betting on pressure from the international community and military defections to oust Maduro. But so far, top military leaders in Venezuela have remained loyal to Maduro. He has called for peaceful, nationwide demonstrations on Wednesday and Saturday to force Maduro's government to hold elections and reiterated that a national assembly amnesty law would protect soldiers and police officers who defect.

Although it has been shunned by the U.S., most Latin American countries and many European leaders, Maduro's leftist government continues to have the strong backing of several countries, including Cuba, Bolivia, Russia and China.