Park Jung-hee`s administration had pursued nuclear missile development despite strong opposition from the United States, so why did they decide to abandon nuclear weapons and devote solely to missiles? To answer this question, this study makes use of process tracing, while contributing to academic debate in two ways. First, this study reviews the historical evidence by adopting a new comprehensive approach, which breaks the tradition of viewing the development of nuclear weapons and missiles in the days of Park Jung-hee`s administration as two separate programs. Second, nuclear missile development during Park Jung-hee`s administration created a precedent when Korea abandoned the pursuit of nuclear weapons and went on to develop a missile within limits set by the United States, which produced a procedure for alleviation within the alliance.