As Iran celebrates the anniversary of the 1979 Islamic Revolution, its supreme leader has urged people to come out in great numbers in defiance of the US.
Tens of thousands of Iranians have been on the streets of Tehran.
President Donald Trump has threatened to get tough on Iran, telling the country recently it has been put on notice.
Iran's President Hassan Rouhani spoke at the rally on Friday and told the crowds that the new American administration needs to respect Iran. And the country will respond with a "decisive answer" to any threats.
So, what does this latest escalation of tensions mean for Iran and the US?
Presenter: Sohail Rahman
Guests:
Mostafa Khoshchesm - political analyst
Kenneth Katzman - Iran expert with the US Congressional Research Service
Ellie Geranmayeh - policy fellow for the Middle East and North Africa Programme at the European Council on Foreign Relations.
