Nationalism plays a critical role in shaping international relations, influencing how countries craft their policies and interactions with others. Nationalistic ideologies can promote unity and identity within a country, but they may also foster tensions with neighboring nations. These sentiments often drive countries to prioritize their interests in diplomatic relations, sometimes at the expense of international cooperation. Nationalism can encourage strong defense policies and economic protectionism, which can impact global markets and alliances, thus playing a fundamental role in defining the dynamics of foreign affairs.