Iran's Supreme Leader Ayatollah Ali Khamenei is adopting an increasingly defiant tone in response to US President Donald Trump's growing threats of violence against the Islamic Republic.

On Wednesday, the cleric urged the Iranian government to further develop its military capabilities. "Progress cannot be stopped," Khameini said after visiting a defense exhibition in Tehran, "we cannot be satisfied."

In no uncertain terms, he added, "today, our defensive power is well-known. Our enemies are afraid of this."

Trump's and Khamenei's conflicting positions have put the US and Iran on a direct course of collision.

And although Iran is not a major topic of discussion at this year's Munich Security Conference, its shadows can be seen hovering over several global hot spots, especially the ongoing crisis in Gaza. In this respect, Iran remains a security challenge not only for the US, but also for Europe.

What's behind Khamenei's defiance?

"The diplomatic overtures by Trump towards Khamenei, coupled with his administration's announcement of a 'maximum pressure' policy toward Tehran, has weakened Khamenei's position," Damon Golriz, a strategic analyst at The Hague Institute for Geopolitics, told DW.

"In recent weeks, numerous senior [Iranian] officials have demonstrated considerable willingness for direct negotiations with Trump," he said, adding that Khamenei's opposition to the US-Iran nuclear talks stems from his "diminishing domestic and regional authority."

Last year's fall of Bashar Assad's regime in Syria — a longtime ally of Iran — severely damaged Tehran's regional standing. Domestically, too, Khamenei is under pressure.

"The most important source of Khamenei's fear is domestic rather than external," said Hossein Aghaie, a senior security and geopolitics analyst. He believes the worst-case scenario for Iran’s supreme leader would be one in which what Aghaie called the "silent majority" of alienated Iranian citizens took advantage of the "window of opportunity" offered by US threats to rise up against an ayatollah weakened and distracted by external pressures.

Khameini's anti-US stance could therefore also be seen as an attempt to counter domestic threats to his position.

Can Trump use military force against Tehran?

A particular point of contention between both nations remains Iran's nuclear capabilites. "Denying Iran all paths to a nuclear weapon" is a centerpiece of the Trump administration's maximum-presure strategy. 

In this regard, however Aghaie believes, "the US under the Trump administration is likely to refrain from engaging in large-scale conflict."

"However, given that Iran's advanced nuclear program is seen as a global security threat, President Trump is weighing options to prevent the regime from building a nuclear weapon, including preventative airstrikes," he added.

To avoid this, experts agree that Iran should give diplomacy a chance. "The ball is in Iran's court now," said Aghaie. He believes that reaching a nuclear peace deal, as floated by Trump, "is possible, but not highly probable."

"The regime believes that if it enters talks with the US, it would have to give massive concessions to Trump on a variety of sensitive issues, including its ballistic missiles, drone programs, as well as its proxy networks," so the expert. "Hence, Tehran is seen as preferring prolonged and inconclusive talks."

What's next for Iran?

Beyond short-term concerns of further violence in the Middle East, strategic analysts Golriz believes that, in the long-term, the US requires a strategy for engaging with Iran that can transform the country into one that can peacefully co-exist in the region, and in the international community.

"However, Trump's approach favors short-term agreements with dictatorial powers. This is evident in his administration's withdrawal from the UN Human Rights Council. I believe his tactics toward Iran will attempt to combine credible military threats with tough economic sanctions," he said.

But for Masih Alinejad, a US-based Iranian activist, Trump's short-term approach carries a lot of significance, as, in her view, the international community is not doing enough to deal with Iran's hardline regime.

"Nuclear negotiations will allow the Iranian regime to buy time and regroup," she told DW on the Munich Security Conference sidelines. The time to act is now, she stressed.

"Iran is at its weakest right now," she argued. "The country's lower and middle-income groups are no longer supporting the Islamic regime. People are fed up. They want to lead a normal life." 

Edited by: Maren Sass