It's not unusual to hear chants of "Death to America" and "Death to Israel" in Tehran.
This week, though, those chants sound more chilling.
That's because tensions between Tehran and Washington are rising rapidly.
Iranian leaders blame the US and Israel for the assassination Wednesday of an Iranian nuclear scientist.
American officials, on the other hand, are publicly warning Iran not to cross a couple of "red lines."
One is the development of nuclear weapons.
The other is blocking the oil shipping lanes at the strategic Strait of Hormuz.
Marco Werman talks with Borzou Daragahi, middle east correspondent for the Financial Times, about increasing tensions between the US and Iraq.