U.S. President Donald Trump escalated tensions with Iran on Sunday by threatening unprecedented military action if Tehran fails to agree to a new nuclear deal, while Iranian leadership formally rejected direct negotiations.

'If they don't make a deal, there will be bombing. It will be bombing the likes of which they have never seen before,' Trump said in an interview with NBC News [8][15]. He also threatened to impose secondary tariffs on Iran, similar to measures taken during his first term.

Iranian President Masoud Pezeshkian confirmed that Iran had responded to Trump's March 12 letter through Omani intermediaries, ruling out direct talks while leaving the door open for indirect negotiations [9][30].

'We don't avoid talks; it's the breach of promises that has caused issues for us so far,' Pezeshkian said during a televised cabinet meeting. 'They must prove that they can build trust.' [9]

The diplomatic standoff comes amid heightened regional tensions, with the U.S. conducting airstrikes against Iranian-backed Houthi rebels in Yemen and ongoing conflicts in Gaza. A February report from the UN's nuclear watchdog indicated Iran has accelerated production of near weapons-grade uranium [9][15].

Trump withdrew the U.S. from the 2015 nuclear deal during his first term and reimposed sanctions on Iran. His administration has maintained that Iran must be prevented from acquiring nuclear weapons, while Tehran insists its nuclear program is for peaceful purposes only [7][11].