What extended deterrence strategies are available to nuclear patrons and what factors determine which strategy they will adopt? How does each strategy manifest as force employment? The bulk of extended deterrence literature focuses on its effectiveness. The question of how nuclear patrons select between and employ strategies of extended deterrence, however, has largely been overlooked. This dissertation aims to answer the questions by identifying the divergent causal paths that lead patrons to develop a distinct extended deterrent posture over time and across clients. Addressing the first, or strategy adoption, question, I argue that the interaction of two variables—1) the type of threat posed to a client by an enemy and 2) the likelihood of an enemy’s quick victory over a client—determines a nuclear patron’s strategy among four options: “forward nuclear deployment,” the “nuclear defense pact,” “forward conventional deployment,” and the “conventional defense pact.” More specifically, I predict that when a patron judges that the enemy’s quick victory is highly likely and a client faces an existential threat, a patron will adopt a strategy of “forward nuclear deployment.” Second, when the enemy’s swift victory seems unlikely and a client is under an existential threat, a patron will adopt a “nuclear defense pact” strategy. Third, when the enemy’s swift overrun of a client is likely and a client faces only a non-existential threat, a patron will adopt a “forward conventional deployment” strategy. Finally, when the enemy’s swift victory seems unlikely and a client faces a non-existential threat, a patron will adopt a “conventional defense pact” strategy. Addressing the second, or strategy implementation, question, I argue that each strategy is characterized by a unique mix of conventional and nuclear assets prepositioned in either forward or rear areas. “Forward nuclear deployment” is embodied as the combination of on-shore tactical nuclear weapons and substantial conventional shield troops along the frontline. Second, a “nuclear defense pact” is comprised of off-shore strategic nuclear forces coupled with conventional token forces in the rear area of the client’s soil. Third, “forward conventional deployment” is manifested as sizable conventional frontline troops, but an absence of any prepositioned nuclear assets. Lastly, a “conventional defense pact” contains neither conventional nor nuclear forward military presence. To substantiate my argument, I examine four cases of extended deterrence: 1) US extended deterrence to NATO-Europe, 2) US extended deterrence to South Korea, 3) US extended deterrence to the Philippines, and 4) Soviet extended deterrence to Cuba. Subsequently, I conclude the dissertation by providing policy implications for contemporary international security challenges, along with directions for future research.