IF Iran does not sit down with US diplomats to discuss scrapping its nuclear ambitions on Saturday, massive bombing raids - and the prospect of an extended and costly US/Iran conflict could result, a national security expert warned today. Historically Tehran has refused to meet US negotiators as a matter of political principle but Donald Trump is demanding face-to-face meetings with top political and military brass from both nations.

He has already announced the two countries will meet in Oman on Saturday - but Iran almost immediately contradicted the president insisting the talks would be conducted through an intermediary. Speaking from the White House’ Oval Office last night Trump warned Iran “would be in great danger” if the projected talks were stymied. He said: “We're having direct talks with Iran, and they've started. It'll go on Saturday.

"We have a very big meeting, and we'll see what can happen. And I think everybody agrees that doing a deal would be preferable.

“Iran cannot have a nuclear weapon, and if the talks aren't successful, I actually think it will be a very bad day for Iran".

In recent days the US has been bolstering military assets in the Middle East. One carrier strike group is already operating in the region and a second is en route from Asia.

B-2 Spirit stealth bombers, which can be armed with nuclear weapons, have also been sent to the Indian Ocean base of Diego Garcia, comfortably in range of Iran.

Dr Oz Hassan, Reader of National Security in the Department of Politics and International Studies, at The University of Warwick, told express.co.uk Trump was more than capable of starting a war with Iran - but that it could bog America down in the region for a long time.

He said: “Donald Trump’s threats to bomb Iran should not be dismissed as empty words.

“While Trump often uses tough language to pressure rivals, his actions suggest he is prepared to follow through—making the risk of military escalation very real if tensions rise again.

“If the United States were to bomb Iran, what it looked like would depend on the goal. A small, targeted strike—perhaps on a nuclear site—might send a message but wouldn’t do much to stop Iran’s nuclear programme.

“A serious attempt to destroy Iran’s capabilities would require a large, complex military operation, involving stealth bombers, powerful bunker-busting bombs, and attacks on Iran’s air defences and military systems. This would look less like a quick raid and more like the start of a major war.”

Iran and geopolitics expert Dr Pierre Pahlavi, who is Chair of the Department of Security and International Affairs and Deputy Director in the Department of Defence Studies of the Canadian Forces College in Toronto, added: “While it is still unlikely that the US will engage in full-scale war with Iran, it remains possible that targeted bombings of Iranian infrastructure and nuclear facilities could take place.

“There is nothing preventing the US from delegating this task to its Israeli allies, offering more or less direct logistical support.

“The idea here is once again to use military pressure as a bargaining chip to push the Iranians into negotiations, particularly those involving their nuclear program.”

Many observers note that Ayatollah Khamenei and the hated theocracy in Iran is weaker than it has ever been right now.

A major protest group the National Council for Resistance of Iran is growing stronger both inside and outside of Tehran, offering a, democratic and gender-equal alternative to two generations of dictatorship.

Last week a group of 100 prominent Iranian American scholars and professionals in a letter to President Trump urged the US government to adopt a principled and informed policy toward Iran, aligning with the aspirations of the Iranian people.

They wrote: “This movement for change is powered by the Iranian people and their organised resistance.

“It requires neither foreign boots on the ground nor financial assistance under any circumstances. The Iranian people’s vision is forward-looking and not tethered to the past. They categorically reject all forms of dictatorship, opposing both the Pahlavi dynasty and the current ruling theocracy.

“The National Council of Resistance of Iran (NCRI) that serves as a coalition of Iran’s democratic forces. Under the leadership of its President-elect, Mrs. Maryam Rajavi, the NCRI has articulated a clear and comprehensive vision for Iran’s future through her 10-point plan.

“The overthrow of the regime and a peaceful, smooth transition require an alternative with a strong presence on the ground, a well-structured organization, and a coherent program. The Resistance Units of the MEK, the principal constituent organization of the NCRI, represent the pivotal force for regime change and a stable transition.”

The Iranian Americans stressed that in recent years the Iranian regime had heavily relied on Reza Pahlavi, the son of the deposed Shah, to undermine the democratic opposition, despite his lack of legitimacy among the Iranian people.

“Pahlavi’s call for ‘maximum support’ is a plea for financial backing from the United States and other countries, further undermining his credibility,” the academics wrote.

They urged U.S. policymakers to recognize the Iranian people’s organized resistance and support their democratic aspirations stating the future of Iran lies in the hands of its people, not in the shadow of its past, nor in the grip of its present oppressors.