The present article investigates the major directions and priorities of Republic of Korea’s defense policy during the period of the Fourth–Fifth Republics under the Chun Doo-Hwan rule (1979–1987). An attempt is taken to outline both domestic and international context of defense policy-making in ROK, to reveal the basic instruments of defense policy implementation and to assess the changes brought by Chun Doo-Hwan’s administration. In his military-political course, Chun Doo-Hwan carried forward many of the initiatives of his predecessor Park Chun-Hee. However, he made significant adjustments that were of a more compromise nature. The major outcomes of Chun Doo-Hwan’s defense policy were the significant progress in military-technical development, the transition from isolated projects to mass production of South Korean made military equipment, reduced dependence on the US financial support, the introduction of a more efficient system of defense budgeting and planning, the transformation of relations with the US, the main military ally of ROK, as a result of which Seoul became an equal partner of Washington rather than a client state. Nevertheless, despite the lesser reliance on economic support, South Korea failed to achieve full political independence from the US, since Chun’s regime that came to power through a military coup, needed support of the ally to ensure its legitimation. In this regard, South Korea had to make some concessions to the US, inter alia dismantling its nuclear weapons program launched by the previous administration, temporarily suspending the ballistic missile program and disbanding a large part of the scientific staff involved in missile development, as well as voluntary agreeing to comply with restrictions on the ballistic missile development under the US–ROK 1979 bilateral treaty. The present study is based on such primary sources as ROK Defense White Paper (the major document of South Korean defense policy) and other official documents of ROK and the US.