Final answer:
National interests refer to a country's goals for security, economic prosperity, and welfare, which shape its foreign policy. This policy now includes various global concerns and the national interest argument can be both a guide and a contentious point for protectionism.
Step-by-step explanation:
The term national interests most commonly refers to the goals or objectives that are deemed important for a nation's security, economic prosperity, and overall welfare. These interests usually guide the creation and implementation of a country's foreign policy. Foreign policy has evolved to address a wide array of issues such as military power, trade, finance, human rights, environmental concerns, and cultural exchanges. The complexity increases as nations must consider their dependencies on key products, like oil, and assess their needs for materials and technologies critical to national security. However, the use of the national interest argument for protectionism can be problematic as it may lead to biased subsidies and decisions that benefit certain industries under the guise of strategic importance.