Sandwiched between Iraq, Afghanistan and Pakistan, it seems almost miraculous that Iran hasn't suffered a major act of domestic terrorism in over 15 years. But that changed on June 7 when twin attacks in Tehran left 17 dead and around 50 injured. The Islamic State swiftly claimed responsibility for the attack, and the Iranian security apparatus switched into high gear, working to round up suspects and prevent other plots from culminating. Iran has always tightly protected its core territory, even if the country's restive periphery has traditionally been a source of instability. Now Tehran is concerned about the southeastern and northwestern reaches of the country, especially growing militancy among the Kurdish and Sunni minority groups that live there.