Even though the United States refused to sign the Versailles Treaty, thereby isolating themselves diplomatically, they were still very much involved in the world how?

Even though the United States did not sign up for the security that the Versailles Treaty offered, they still played a big role economically around the world after World War I. The United States became the world's leading economic power after WWI. They were a major creditor to the defeated nations in Europe.

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he sent troops to protect the students as they entered the school.