What do we know about what's happening in Iran?

What do we know about what's happening in Iran? The country has been rocked by days of large antigovernment protests. First, sparked by the crippling economy, now anger at the theocratic regime. More than 500 people have been killed, according to the U.S.-based Human Rights Activists News Agency. NPR is unable to independently confirm that figure. And now President Trump is considering whether to weigh in – and how. Sanctions. Cyber attacks. Military strikes. President Trump keeps suggesting the United States may get involved. If so, when and how?