Faced with a host of external national security challenges, very few observers pay attention to a key emerging internal security and governance issue in Iran: domestic migration. In the Iranian migration debate, the focus is commonly on those who move abroad. But there are also domestic as well as regional flows of population groups that are putting pressure on the authorities.

Some have sought to highlight the scale of the challenges ahead. In 2015, former head of the Department of Environment Issa Kalantari warned that environmental issues—especially the water crisis—could force millions of citizens to migrate internally. Studies also point to other major causes of internal population movements. Underdevelopment and unemployment are additional key factors, as displayed by how...