For the last 60 years, maintaining a strong bilateral alliance with the United States has been the key focus of South Korea’s alliance strategy, though not always solid. The alliance has been central to the national security and economy of the Republic of Korea. It has played pivotal role in deterring the North Korean threat and in contributing to political and economic stability in South Korea and even Northeast Asia as a whole. The transfer of wartime operational control has, however, faced severe opposition from conservative groups who claim that it may make the ROK security situation more un-stable by weakening the ROK-US alliance and by provoking an arms race amongst neighboring states. In addition, it could, they argue, cause an economic crisis due to the heavy expenditure involved in replacing US forces with Korean ones. Nevertheless, the transfer is scheduled for December 2015 even though the recent government makes moves in order to seek another delay of the wartime operational control. Under these backdrops, this study focuses on how two states strategically cooperate after transferring wartime operational control on the assumption of the OPCON would be transferred as scheduled or some time when North Korean regime still exists. For this, it firstly will explore why two states should strongly cooperate with each other in the future. Then, it will explain the main debate on the transfer of wartime operational control in South Korea. Lastly, it will suggest some strategic options for cooperation between the ROK and the US under the new direction of operational control.