The Gaza conflict that erupted in October 2023 not only reignited the longstanding tensions between Israel and Palestinian militant groups but also highlighted the critical importance of another strategic fault line: the ongoing confrontation between Israel and Iran (or the “Axis of Resistance”). This chapter first analyzes the background, origins, strategic logic, and implications of Iran’s “forward defense strategy,” an attempt at the economic and military support of pro-Iranian non-state armed groups abroad, aimed at exerting military pressure on the United States and its allied forces during peacetime and utilizing that pressure for deterrence and compellence. Following this, I will discuss the various groups that constitute the “Axis of Resistance,” particularly Hezbollah in Lebanon, Hamas in Palestine, the Houthi Movement in Yemen, and “Iran-backed Militias” in Syria and Iraq. For each of these groups I will examine their organization, objectives, strategies, and strategic significance for Iran.