Three weeks into the largest uprising in the Islamic Republic’s history, the country has gone dark.

With the internet shut down and security forces unleashed, thousands — possibly tens of thousands — of Iranians have been massacred in an unprecedented and brutal crackdown.

Behnam Ben Taleblu joins Bill to unpack what this revolution means, why defections — not protests — are the real tipping point, and why the West’s failure to act may leave permanent scars — on Iran, and on U.S. credibility.