WASHINGTON — Senior officials in the Trump administration are convinced the Iranian regime is vulnerable to collapse and that tough U.S. economic sanctions could hasten its demise, foreign diplomats and former U.S. officials told NBC News.

President Donald Trump himself has questioned if the regime can last.

"When I came in here, it was a question of when would they take over the Middle East," Trump said in an August interview with Bloomberg News. "Now it's a question of will they survive. It's a big difference in one and a half years."

But European allies and intelligence experts disagree, and see Washington's forecast as a case of wishful thinking. While acknowledging the regime's growing economic and political troubles, European governments believe the Iranian leadership remains firmly entrenched and that any attempt to topple the government could produce a worse outcome, the diplomats said.

In meetings with foreign counterparts, Secretary of State Mike Pompeo, National Security Adviser John Bolton and other officials have argued the regime is fragile and increasingly unable to manage a troubled economy and a frustrated population, according to nine foreign diplomats. They cite rising inflation, strikes and sporadic protests as telltale signs of a regime at risk, and that U.S. sanctions on its oil exports — which came into effect this week — could deal a crippling blow that will force Tehran to abandon its military adventures in the Middle East or even lose its grip on power.

"That's their logic," said one European diplomat, who disagrees and spoke on condition of anonymity. "They are saying the regime is going to fall."

U.S. intelligence agencies have also not detected signs that the Iranian regime is on the verge of unravelling, U.S. officials told NBC News. They see a regime that appears to be just as firmly in control as it has been for years. But they said they do see a country with mounting headaches, and think U.S. sanctions aimed at cutting oil revenues could cause real difficulties for the regime

"The Trump administration's policies appear designed to add to the political stress which already exists within Iran," a former U.S. intelligence official said.

Pompeo, Bolton and other top officials publicly insist the administration is not pursuing regime change, and that their policy is merely aimed at changing the regime's behavior.

"We certainly don't like this regime. It's a deeply hypocritical religious dictatorship that robs its people blind," a State Department official, who was not authorized to speak on the record, told NBC News. "Ultimately, it's up to the Iranian people to decide what government they want to live under. ...We want the Iranian people to be successful. We hope they can restore democracy there."

Bolton has a long track record of public statements calling for weakening the regime and ultimately replacing it. Eight months before he was named by Trump to his current job, Bolton gave the keynote address to the annual convention of the Peoples' Mujahedin of Iran, an anti-regime group known in the Iran as the MEK: "I have said for the over 10 years that I've been coming to these events that the declared policy of the United States of America should be the overthrow of the mullahs' regime in Tehran."

National Security Adviser John Bolton, left, and Secretary of State Mike Pompeo attend a meeting at the Eisenhower Executive Office Building in Washington, D.C. on Oct. 11, 2018. Handrew Harrer / Bloomberg via Getty Images

In language reminiscent of Cold War rhetoric, Secretary of State Mike Pompeo has made a point of expressing solidarity with the Iranian people and appeared to invite them to oust the clerical leadership.

"In light of these protests and 40 years of regime tyranny, I have a message for the people of Iran: The United States hears you; the United States supports you; the United States is with you," Pompeo said in a July speech before an audience of Iranian-Americans in Los Angeles.

"And you should know that the United States is not afraid to spread our message on the airwaves and online inside of Iran either," said Pompeo, announcing plans to launch a 24-hour Farsi-language channel.

The administration has launched an aggressive information war against Iran on social media and a virtual embassy site, ridiculing Iranian leaders over corruption, air pollution, water shortages and the repression of dissidents.

Hawks close to the administration see many parallels between Iran and the former Soviet Union, and maintain that the current president could play a role similar to former President Ronald Reagan by taking a tough, uncompromising stance toward the regime in Tehran.

"We don't know that the regime is going to collapse. And we don't know when," said Mark Dubowitz, chief executive of the Foundation for Defense of Democracies, which backed the administration's exit from the Iran nuclear deal. "But we sense that this regime is a lot weaker than people believe, and that there's something rotten at the heart of the Islamic Republic in the same way that there was something rotten at the heart of the Soviet Union."

The Soviet analogy has sparked an internal debate among conservatives in Washington, with commentator and author Fred Kagan cautioning that the comparison is not precise and that the rulers of Iran could yet hold on to power for some time.

Iran's economy has come under serious strain over the past year, partly because of renewed U.S. sanctions and partly because of years of government mismanagement, experts say. The rial has plunged to record lows, losing 70 percent of its value. The IMF predicts the average inflation rate could surpass 34 percent next year, major European firms have pulled out and there are periodic shortages due to panic buying of staples. Teachers and truck drivers have staged strikes and thousands protested in cities across the country in December and January over rising prices and alleged government corruption.

European diplomats and experts say the protests and strikes are focused on specific grievances and have not evolved into a broader political movement.

"It would take a lot more than what's happening now to produce a collapse or regime change," said another European diplomat who asked not to be quoted by name.

Iran's President Hassan Rouhani has warned the country that U.S. sanctions will cause economic pain but vowed his government would resist the pressure.

"We are in a war situation," Rouhani said. "We are in an economic war situation. We are confronting a bullying enemy. We have to stand to win."

Unlike a previous pressure campaign led by the Obama administration between 2012-2015, the United States is leading a unilateral sanctions effort without political support from Europe and with Russia signaling it intends to throw Iran an economic lifeline.

Even if Iran survives the latest squeeze by Washington, the Islamic republic appears to be descending into a long-term decline, said the former U.S. intelligence officer.

The Islamic republic's "revolutionary energy has dissipated over the years," he said, and the country's youth are acutely aware of a more open, prosperous life elsewhere.

He cautioned, however, that the end is not necessarily near, in part because the Revolutionary Guard is well-placed to crush opposition and maintain the regime's hold.

"Although Iran appears increasingly fragile, it does not appear on the verge of a collapse," he said. The Revolutionary Guard "appears to remain well-resourced, organizationally-cohesive, and its units are distributed around the country."

Another former intelligence officer, John McLaughlin, who served as deputy director and acting director of the CIA, said that the regime at the moment faces no organized, unified opposition.

"Major outbreaks against the government, in 2009 and before have been hampered by factionalism among the protesters and no unified leadership -- making it relatively easy for security forces to squelch opponents," McLaughlinsaid.

"I've seen no evidence that this has changed, so we should not hold our breaths waiting for the great successful uprising along the lines of what we saw in Eastern Europe 30 years ago."

A vehicle burns as demonstrators protested high prices and the poor state of the economy in Dorud, in Iran's Lorestan province, on Dec. 30, 2017. SalamPix / Abaca/Sipa USA via AP

Given the absence of a viable opposition, destabilizing the regime could merely produce an even more aggressive government dominated by the well-armed and well-funded Revolutionary Guard, former officials and European diplomats said.

"They don't have a plan for what comes next," said one diplomat. "It's very scary."

If the regime did unravel, it's unlikely it would produce a straight-forward transition to a more responsible or more representative government, said Suzanne Maloney, an Iran expert at the Brookings Institution.

"There's just no precedent in the region's history or Iran's history that this all ends all quickly and neatly and to our advantage," Maloney said.