How did ideas about nationalism affect the way u. s. leaders saw the united states' role in world affairs?

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The correct answer to this open question is the following.

Ideas about nationalism affected the way U.S. leaders saw the United States' role in world affairs in that the US government considered a priority to foster and support the American culture, customs, and traditions, and though to expand its territories and protect its interests abroad. President James Monroe created the Monroe Doctrine, which established that European countries should never intervene again in the issues of the American continent.

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