The dynamics of tensions between the United States (US) and China in the South China Sea show complex challenges in 21st century international relations. The South China Sea, rich in natural resources and a strategic trade route, has become a focal point of competition between the two great powers. China’s territorial claims to this sea area, which includes the Spratly and Paracel Islands, are often challenged by regional countries such as Vietnam, the Philippines and Malaysia. China uses the “seven artificial islands” policy to strengthen its claims, which has an impact on regional stability. Meanwhile, the US supports freedom of navigation and the right of other countries to explore resources in these waters. Frequent military exercises conducted by the US, such as freedom of navigation operations (FONOPs), aim to challenge China’s claims and defend international rules. In the past year, the intensity of FONOPs has increased, reflecting the US commitment to its allies in Southeast Asia. On the other hand, China is building its naval fleet, increasing patrols and observations, and making firm statements regarding its territorial sovereignty. The development of military technology, especially fighter aircraft and drones, has further strengthened China’s position. Use of these capabilities increases security and surveillance in contested areas. China is also carrying out economic diplomacy, with the Belt and Road Initiative (BRI) project as a tool to expand its influence in the coastal countries of the South China Sea. Meanwhile, the US is trying to build alliances, such as the Quad (US, India, Japan, Australia), to challenge China’s dominance in the region. Human rights issues, particularly in Xinjiang and Hong Kong, also affect US-China relations. The US’s tough stance on human rights abuses is broadened by criticism of China on bilateral and regional issues. In this increasingly polarized situation, both sides have little room for compromise. Russian influence is also apparent in these tensions. As China’s ally, Russia supports China’s claims in the South China Sea and increases military cooperation with Beijing, exposing the US to multidimensional challenges. The impact of these tensions is not only felt by the countries directly involved, but also by the global economy, where these waters are the main shipping routes for goods and energy. Dynamic geopolitical conditions, coupled with multilateral diplomatic efforts by ASEAN and other countries to resolve disputes peacefully, provide hope for easing tensions. The involvement of third parties and the use of international forums can provide constructive solutions. These tensions demand continued attention and careful resolution, given their far-reaching impact on regional stability and global security.