Refugees who joined the largely overlooked Fatemiyoun Brigade to battle for Shiite Islam and escape crushing poverty had become a force in Tehran’s proxy wars.
Iran-backed forces are assembling drones and retrofitting rockets in the territory of an American ally. They are used in attacks on U.S. outposts in Iraq and Syria.
Officials from Iran and Hezbollah helped plan the attack, people familiar with the operation said, but the U.S. and its allies have not found evidence directly linking Tehran.