The conflict between the U.S. and China has taken a more serious turn as China raised its responsibility for the Corona 19 Pandemics, tightened sanctions on Huawei, and China’s enforcement of the Hong Kong Security Law. The U.S.-China conflict, which was reignited in 2020, has raised concerns over a new Cold War due to the rising possibility of military conflict and ideological disputes between communism and democracy, in addition to the aforementioned issues. A clearer diplomatic strategy is required for South Korea and other Indian and Pacific countries, including South Korea, which are directly affected by the U.S.-China trade dispute, strengthening protectionism, the global economic slowdown, military tensions in the Indo-Pacific region, and concerns over economic retaliation. Korea, other middle-power countries and ASEAN countries should strengthen international relations through the protection of the current liberal international order and the pursuit of universal values such as peace, human rights and democracy, and make efforts to find a solution within the current liberal international order to prevent the U.S.-China hegemonic rivalry from turning into war rather than to choose either the U.S. or China from taking sides. This study sought to determine the cause of the U.S.-China hegemony competition based on the theory of offensive realism, and predicted future U.S.-China relations by analyzing the confrontation between the U.S. and China. It considered the responses of ASEAN countries, a geopolitical battleground of the U.S.-China hegemony competition, and predicted that security cooperation with ASEAN through the New Southern Policy and the strengthening of the liberal international order could serve as a precautionary note to prevent war, the conclusion of the hegemonic competition between the U.S. and China in aggressive realism by partially offsetting the aggressiveness of the U.S.-China hegemony competition by rules and institutions.