United States President Donald Trump's decision to withdraw from the nuclear deal signed with Teheran and the European powers doesn't just make it likelier that Iran, too, will abandon the treaty and renew its push to make a bomb.

It could also determine if the social unrest sweeping the Islamic republic deepens and further destabilises the regime. The government is facing perhaps its greatest opposition nationwide since the 1979 Islamic revolution. Mr Trump's decision will change how that story plays out in ways that will further destabilise the regime while giving conservatives more power for now.