In recent decades, the Islamic Republic of Iran has poured roughly $50bn into foreign interventions. Despite facing sanctions on par with North Korea and being an international pariah, Iran has created its own sphere of influence, helping propel Hamas, the Houthis and Hezbollah to the forefront of the region in the process. The futures of Iraq, Lebanon, Syria, Palestine and Yemen are intertwined with the fate of the Islamic Republic. What spurred Iran’s rise – and what are its motivations now? Mohsen Milani makes the case that Iran is guided by two principles: power and deterrence. The Iran–Iraq war provided Iran the impetus to build its own military-industrial complex, while its funding, training and arming of Hezbollah – the only army not to lose against Israel – acts as a warning for anyone with designs on Iran’s territory. But power has a price. As domestic unrest rises, Iran simply cannot afford its attempts at regional dominance any longer.