The policy changes of a country in international affairs are affected by a variety of complex factors, which interact to form a dynamic decision-making environment. The following is an itemized analysis of the main influencing factors： --- ###**1. Domestic factors** 1. **Political system and power structure** -Change of government or change of leaders (such as the policy shift of the United States from Trump to Biden). -Ideological differences between political parties (for example, left-wing governments may pay more attention to human rights diplomacy, while right-wing governments tend to be realistic). -Lobbying by interest groups (military industry and energy companies influence foreign policy through political contributions). 2. **Economic situation** -The economic crisis may promote protectionism (such as trade barriers after the 2008 financial crisis). -Resource-dependent countries adjust their diplomatic strategies (such as Saudi Arabia's oil policy affecting its international alliance). 3. **Society and culture** -Pressure from public opinion (many European countries have tightened their refugee policies due to popular opposition). -Nationalist sentiment (India's ”self-reliance" policy is related to the rise of domestic nationalism). -Historical memory (for example, Japan's peaceful constitution restricts its military operations). --- ###**2. International system and external environment** 1. **Changes in the international landscape** -Transfer of power (China's rise has prompted countries to adjust their Indo-Pacific strategies). -The role of multilateral mechanisms (United Nations sanctions force Iran to adjust its nuclear policy). -Changes in alliance relations (Turkey has strengthened its cooperation with Russia due to tensions with the United States and Europe). 2. **Security threats and conflicts** -Military conflict (the crisis in Ukraine triggered European countries to strengthen NATO cooperation). -Non-traditional security challenges (climate change promotes the signing of the Paris Agreement by many countries). 3. **Economic globalization and interdependence** -Supply chain dependence (the new crown epidemic has exposed the dependence on medical supplies, and many countries have promoted localized production). -The influence of multinational companies (the EU has passed the "Digital Market Law" to regulate technology giants). --- ###**3. International norms and legal constraints** 1. **International law and treaty obligations** -The Nuclear Non-proliferation Treaty restricts the nuclear policies of relevant countries (such as North Korea's withdrawal triggering international sanctions). -Rulings of the International Court of Justice (such as the South China Sea Arbitration case affecting the Philippines' strategy towards China). 2. **International public opinion and moral pressure** -”Human rights diplomacy" pressure (Western accusations on the Xinjiang issue affect China's international image). -Environmental protection movement promotion policy (Sweden's "environmental girl" Tunberg promotes the EU's green policy). --- ###**4. Technology and sudden events** 1. **Technological revolution** -The improvement of cyber warfare capabilities has prompted countries to formulate cyberspace rules (such as the Cybercrime Convention). -Artificial intelligence competition promotes the decoupling policy of Sino-US technology. 2. **Sudden crisis** -Public health events (the new Crown epidemic accelerates the competition for vaccine diplomacy). -Natural disasters (adjustment of global nuclear power policy after the Fukushima nuclear accident in Japan). --- ###**5. Leadership characteristics and decision-making mechanism** 1. **Personal factors** -The character of the leader (Putin's tough style shapes Russian diplomacy). -Cognitive bias (the George W. Bush administration launched the Iraq war based on false intelligence). 2. **Characteristics of decision-making mechanism** -Centralized countries (such as North Korea, whose policy is highly dependent on the will of its leaders). - Democratic countries need to balance multiple interests (such as the U.S. Congress restricting tariff policies towards China). --- ###**6. Case linkage analysis** -**Sino-US trade war**: Domestic industry protection needs (U.S.), technological competition (“Made in China 2025”), international rule reconstruction (WTO reform) and other factors are intertwined. -**The shift of German energy policy**: The Russian-Ukrainian conflict (security), the rise of green political parties (domestic politics), and the unity of the European Union (international pressure) work together. --- ###**Summary** The change of national policies is essentially a dynamic balance between domestic demand and the international environment. Decision makers need to weigh benefits, costs, and risks, while being subject to historical inertia, institutional constraints, and sudden variables. Understanding policy changes requires a multi-dimensional perspective and avoids single attribution.