He also warned that it would be a “big mistake to do anything” to harm any of the estimated 40,000 to 45,000 Americans in the country or crack down more severely on the political opposition led by self-declared Interim President Juan Guaido.

The U.S. and more than 50 other countries have recognized Guaido as Venezuela’s rightful leader, and the Trump administration is pressuring Maduro to leave power by tightening sanctions on government officials, Venezuelan oil exports and other sectors of the economy. President Donald Trump has also sought to pressure Cuba, announcing Wednesday that U.S. citizens who fled the Castro regime can sue foreign companies that have made use of their former property on the island.

“If you could wave a magic wand and take the Cubans out of Venezuela, Maduro would fall almost simultaneously,” Bolton told Bloomberg News ahead of a speech in Miami on the U.S. campaign to topple Maduro. “That’s really what’s keeping him in power.”

Russia landed two planeloads of troops and military equipment in Venezuela last month, raising tensions with the U.S. Trump said March 28 that the Kremlin “needs to get out” of the country, and Vice President Mike Pence called the move “an unwelcome provocation.” Russia defended the deployment and said the troops would stay as long as they’re needed.

Read more: Russia Defends Deployment in Venezuela After Trump’s ‘Get Out’

Bolton said that National Security Council staff are in Moscow this week discussing Russia’s involvement in Venezuela. Trump wants better relations with Russian President Vladimir Putin’s government, Bolton said, “and we’ve said very clearly that the possibility of adventurism in Venezuela is not going to help in that regard.”

Russia and China “are hedging their bets in Venezuela,” Bolton said. “I think it’s an indication that they see their debts and investments in jeopardy if they back Maduro unequivocally.”

The U.S. Treasury Department on Wednesday sanctioned the Central Bank of Venezuela and one of its directors, Iliana Josefa Ruzza Terán, to raise pressure on Maduro. While most central bank activities by the Maduro regime are restricted, debit and credit card transitions can still be processed, according to a statement from Treasury Secretary Steven Mnuchin.

Maduro has so far weathered the campaign by the U.S. and Guaido to unseat him. A U.S. effort last month to move humanitarian aid into the country in coordination with Guaido failed after Maduro blocked bridges into Colombia and Brazil. Bolton declined to predict how soon the Venezuela leader’s regime will fall.

“There are a lot of different ways it could happen,” he said. “But I do reject the idea that somehow things are fixed, that Guaido has lost momentum.”

“The opposition has held together,” he said. “Over many protests over the last 20 years, the regime was always able to fracture the opposition, and that hasn’t happened yet, despite a lot of pressure — putting people in jail, over 40 people killed by the regime since January.”

Venezuela’s military leaders haven’t turned on Maduro as U.S. official had predicted. But Bolton said that Guaido enjoys widespread support among the military’s rank-and-file, and that’s prevented Maduro from ordering the arrest of his opponents.

“The reason he didn’t is because he fears, correctly, that they would not have carried that order out,” Bolton said. “And then his regime would have collapsed.”

Trump and other U.S. officials have frequently warned that “all options are on the table” when asked if an American military intervention is possible. Bolton said Wednesday that there are lines Maduro could cross to prompt a more muscular U.S. intervention beyond sanctions, though he said he wouldn’t specifically outline them.

“One of the important points here when we say that ‘all options are on the table’ is not to tip our hand to Maduro what we might do or, maybe more importantly, what we might not do,” Bolton said. “And we have said that further repression of the opposition would be a big mistake. It would be a big mistake to harm the 40,000 to 45,000 American citizens who are in Venezuela.

“I think all of these factors and others are weighing on the minds of the top generals and others who have supported Maduro, and I think there’s an increasing realization that his regime is not sustainable.” DM