South Korea is facing a tectonic change of international environment. The original advanced countries are undergoing a stagnation never seen after 1945, while the growth of China and other developing countries is offsetting it globally. South Korea benefited much from the rise of the Chinese economy, the most remarkable benefit being the trade surplus; however, it is disappearing with China’s catch-up in technological capability. The rise of China poses a challenge to the US hegemony, undermining the rule-based order and making East Asia the arena of a hegemony contest, which is most threatening to countries like South Korea. The country needs the ability to manage relationships with the great powers to cope with it, but whether it has the ability is unclear. Compared with the nineteenth century, when Korea failed to adapt to a tectonic change, the overall ability has improved remarkably, but the ability to form domestic cohesion remains the least improved.