The man once celebrated in Tehran as “the living martyr,” Maj. Gen. Qassem Soleimani, is now just a martyr in the traditional sense. Felled by a U.S. drone strike in Iraq, his life ended in the conflict zone that launched his career nearly 40 years ago. As the leader of the deadly Islamic Revolutionary Guard Corps' Quds Force, Soleimani was the lynchpin in Iran’s transnational terrorism apparatus, stretching from Yemen to Lebanon to Latin America and beyond. His death therefore marks a significant political and strategic setback for the Islamic Republic. But this does not mean that the regime’s regional threat network is defeated. The Islamic Republic’s well-trained and amply funded proxies and sectarian allies await the marching orders of Soleimani’s successor. Iran’s Supreme Leader, Ali Khamenei, has called upon Soleimani’s successor, Brig. Gen. Esmail Qaani, to follow an “identical” approach. To understand that approach, it is important to understand its evolution. Soleimani’s two-decade-plus tenure at the helm of the Quds Force, Iran’s elite foreign operations unit, coincided with some of the most significant events in post-Cold War Middle Eastern history. These include the U.S.-led wars in Iraq and Afghanistan, the Arab Spring, and the rise and fall of the Islamic State. Soleimani pursued a strategy during this period of fomenting unrest across the region to bleed Iran’s adversaries using proxies and partners such as Hezbollah, the Houthis in Yemen, and Shiite militias in Iraq....