This paper deals with one of the most critical issues in contemporary international relations: how China’s rise challenges foreign policies of U.S. allies, with a focus on the Republic of Korea (ROK) or South Korea. South Korea has been carefully hedging between the United States and China, its traditional security patron and largest trade partner, respectively. Strategic rivalry between the two great powers has put South Korea in an awkward position as pressure grows from the two powers to pick a side. Using a modified dual-track economics-security nexus framework, this paper suggests that the United States and China each has a significant impact on South Korea’s security and economic policies, making it important but challenging for South Korea to simultaneously manage relations with the two great powers. So far, South Korea has maintained these two sets of relationships remarkably well, but it may be difficult to continue with business as usual in the years ahead. For its own national interests, South Korea must seek to preserve the status quo under which it can continue to benefit from good relations with both great powers. The paper also proposes that South Korea should form a “middle power coalition” with like-minded nations to deflect pressures and avoid the dilemma of having to choose sides.