From the Document: "The United States has supported North Macedonia since its independence from Yugoslavia in 1991 and strongly backs its European Union (EU) and NATO ambitions. (The country's constitutional name was the Republic of Macedonia until February 2019, when it was renamed the Republic of North Macedonia.) On multiple occasions, the United States played a key role in defusing political crises and interethnic tensions in North Macedonia. For more than two decades, a U.S. diplomat led United Nations-brokered negotiations between Greece and then-Macedonia to resolve their bilateral dispute over the latter's use of the name 'Macedonia'. With strong U.S. support, in 2018 North Macedonia and Greece reached the landmark Prespa Agreement, which resulted in the name change and resolved their bilateral dispute."
CRS Report for Congress, R45739
Congressional Research Service: https://crsreports.congress.gov/