Washington (CNN) Secretary of State Mike Pompeo claimed Tuesday that embattled Venezuelan leader Nicolas Maduro was preparing to leave the country for Cuba , but was talked out of it by Russia.

"We've watched throughout the day, it's been a long time since anyone's seen Maduro," Pompeo said in an interview with CNN's Wolf Blitzer on "The Situation Room."

"He had an airplane on the tarmac, he was ready to leave this morning as we understand it and the Russians indicated he should stay."

"He was headed for Havana," Pompeo said.

Russian Foreign Ministry spokeswoman Maria Zakharova suggested that Pompeo's claim was false, telling CNN, "Washington tried its best to demoralize the Venezuelan army and now used fakes as a part of information war."

'Operation Freedom'

Pompeo's comments followed a bombshell revelation by national security adviser John Bolton, who claimed for the first time that some of Maduro's closest allies had been talking to the opposition about ousting him and giving their support to National Assembly interim president Juan Guaido.

"We think it's still very important for key figures in the regime who have been talking to the opposition over these last three months to make good on their commitment to achieve the peaceful transfer of power from the Maduro" regime, Bolton told reporters outside the White House on Tuesday as clashes intensified between regime forces and opposition groups in Caracas.

"All agreed Maduro had to go," Bolton said.

The claims by Pompeo and Bolton amount to an extraordinary move by the US to divide and pressure the Maduro regime after Trump administration officials said they were surprised by Guaido, who pushed up by a day his dawn announcement that he was "beginning the final phase of Operation Freedom" in an escalation of his bid to oust Maduro.

Pompeo reiterated US support for opposition leader Guaido amid an escalating situation in Venezuela. On Tuesday morning, Guaido, standing alongside a group of soldiers in Caracas, announced an uprising, calling it "Operation Freedom," and urged his supporters to take to the streets in an effort to oust Maduro. Confrontations between the two sides turned violent, with at least 71 people being taken to a medical center in the Venezuelan capital.

'Fire up the plane'

Pompeo said he would urge Maduro to "fire up the plane," warning that "the cost for he and those who protect him will continue to increase."

"The harm that he will bring to them will only increase. We implore him, it's time for him to leave, it's time for him to depart Venezuela, and we would urge him to do this at the earliest possible moment," he said.

However, the secretary of state refused to say whether Maduro would be permitted to safely depart for Cuba, instead saying that "Mr. Maduro understands what will happen if he gets on that airplane."

"He knows our expectations," Pompeo said when repeatedly pressed on the question.

While Pompeo noted that the US has told Russia and Cuba that their support for the embattled Venezuelan leader is "unacceptable," he would not say whether he holds Russia responsible for the violence or whether US President Donald Trump had spoken to Russian President Vladimir Putin on the issue.

"I don't want to get into all of the conversations that have been held between us and other parties," Pompeo told CNN. "Suffice it to say, I am confident that the Russians understand the American position on this and understand the harm that is being inflicted on the Venezuelan people."

'The stakes are very high'

Administration officials said talks between senior regime officials and the opposition had been taking place for the last few months and would have allowed them to keep their positions after a transfer of power. Bolton mentioned Vladimir Padrino, Venezuela's minister of defense, as well as Maikel Moreno, the chief judge of the country's Supreme Court, and Ivan Rafael Hernandez Dala, the commander of presidential guard.

But after Guaido made his announcement, flanked by opposition leader Leopoldo Lopez and men in military uniforms, support from the regime officials didn't materialize. Bolton, describing the situation as "a very delicate moment," went before the cameras to name the officials and give them a deadline.

"They need to be able to act this afternoon or this evening to help bring other forces to the side of the interim president," Bolton declared. "They committed to support ousting Maduro and it's time for them now, if the Cubans will let them, to do it to fulfill their commitments."

Bolton and other administration officials didn't provide any proof that the three members of Maduro's inner circle were considering switching allegiance. But he went before the microphones at a critical moment.

"The stakes are very high for Guaido and Lopez," said Kevin Ivers, a Latin American expert and vice president of the DCI Group. "Now the regime has the authority to arrest and possibly kill them, which could be the end of what started in January, with Guaido's move to declare himself president."

Chile's foreign minister tweeted confirmation of media reports that Lopez, his wife and daughter had sought refuge with the Chilean government, going to the ambassador's residence in Caracas.

'A very, very big day'

"If this effort fails today and they are captured I think it could be a very, very serious setback for any legitimate effort to overthrow the regime or restore democracy," Ivers said, "so today is a very, very big day."

Bolton's announcement was both an attempt at damage control in a highly fluid and combustible environment as well as an attempt to strike a blow at the Venezuelan government, said Peter Schechter, a Latin America expert and executive producer of the foreign policy podcast Altamar.

"He's trying to divide the Maduro government and create suspicions and foment all kinds of insider divisions, because the one thing that's kept this government together is that they're all fearful of being extradited to the United States, so they're all trying to do this together," said Schechter.

The disclosures about high level Maduro allies -- particularly Padrino, who is seen as the personal guarantor of Maduro's years-long hold on power -- is extraordinary, said Ivers.

"I have no doubt any of these conversations happened behind the scenes," Ivers said. "That makes absolute sense, but there had never been any indications until now that such efforts had come close to bearing fruit. This would be extraordinary news. It was clearly a message directed at the Venezuelans regime and at specific figures in the Venezuelan regime."

In a statement early Tuesday, Padrino reiterated his loyalty to Maduro. The defense secretary has also been named economic and trade czar, giving him effective control over the flow of goods across the border, including drugs, a lucrative position that is meant to reward him for his loyalty, analysts say.

Bolton warned that if opposition forces fail in their efforts to oust Maduro, the country will sink even deeper into a dictatorship.

"If this effort fails, they will sink into a dictatorship from which there are very few alternatives," Bolton said, adding that President Donald Trump "wants to see a peaceful transfer of power."

'A very delicate moment'

"It's a very delicate moment," he said.

At this delicate moment, Guaido surprised the US, said Elliot Abrams, the State Department envoy on Venezuela. He said the US had been told that Guaido would call for protestors to take to the streets on Wednesday's May Day holiday, and that they hadn't been aware the opposition leader would move forward on Tuesday.

Abrams confirmed there have been high-level negotiations going on inside Venezuela between the opposition camp and regime officials, including the head of the Supreme Court, the defense minister and the head of security.

"In the last month or two, there have been some interesting negotiations among Venezuelans inside the regime and out of the regime about returning to the constitution," Abrams said, mentioning Moreno, as well as Padrino and Hernandez, who are both under US sanctions.

"As I recall of the agreements, all of them were going to retain their positions," Abrams said. He said the US had not been a party to the talks.

"They negotiated for a long time about the means of restoring democracy, but it seems that today they're not going forward, at least as of 3 pm, with the agreements they made," Abrams said. "But we will see what happens in the rest of the day. If you've seen the TV screens, you've know that things are very far from calm and settled in not only Caracas, but around the country."

Abrams said that the worry that Guaido would be arrested "always exists." Pompeo warned that such a move would be considered "a major escalation." The US-educated 35-year-old launched his campaign to return Venezuela to democracy in January.

Indeed, this is a "now or never moment for Guaido," said Michael McCarthy, the CEO of Caracas Wire, "because it's evident he's reaching the end of his honeymoon." Maduro had seemingly retained hold on crucial military support.

McCarthy described Guaido's move as "high stakes," and said the US approach has been equally so, with its tendency "to talk tough on this issue."

Indeed, both Bolton and Pompeo said "all options" remain on the table. When pressed by Blitzer, Pompeo said the administration stood behind that threat. "The President has made very clear that all options are on the table, that includes a military option," Pompeo said, adding that he's "hoping" it won't be necessary.

"I don't think anyone should be fooled that if the President makes that decision" the United States military "has the capacity to execute."

Many analysts, however, said it was unlikely the administration would use military force.

Planning for 'the day after'

"While the US has never taken the military option off the table, the US doesn't have forces in the area sufficient for an invasion," said Ivers. "It would be far more difficult even than Iraq. The terrain, the number of Venezuelan forces, it would have been a much bloodier conflict."

And Ivers added that armed US intervention -- something Guaido supporters have said they do not want -- "would have meant an end to international support for Guaido, but they always left it on the table to ensure the regime knew they meant business, this was a serious effort, not just for show."

Bolton said the US would continue "planning for what we call 'the day after,' the day after Maduro," adding that "it's been very much on our mind. ... Those plans are moving ahead, we're trying to refine them," he said.

In the meantime, Risa Grais-Targow, director of the Latin America program at the Eurasia Group, wrote that key "signposts to watch in the coming hours and days are additional defections from within the armed forces, not only in terms of the number, but also in terms of the profile of figures who are defecting."

A key variable, she said, will be whether those figures command troops, whether those troops are loyal to them, how many of them there are and their ability to threaten the government militarily.