Iran's Foreign Minister Mohammad Javad Zarif has downplayed US President Donald Trump's "genocidal taunts" but warned Trump Iran would not be intimidated by them.

However, on Monday Iran quadrupled its rate of production of low-enriched uranium.

Both sides have been trading threats while signalling they were still open to negotiation.

Al Jazeera’s Patty Culhane reports from Washington, DC.

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