Moncada graduated in history at the Central University of Venezuela. Between 2004 and 2006, he was Minister of Higher Education of President Hugo Chavez and director of the History School of the Central University of Venezuela. Moncada was Ambassador of Venezuela to the United Nations in 2013. He also was Venezuela's ambassador to the United Kingdom of Great Britain and Northern Ireland. Later, he served as Ambassador of Venezuela to the Organization of American States and as head of the Presidential Commission of the Non-Aligned Movement. Moncada assumed the Vice-Ministry for North America, and then replaced Delcy Rodríguez as Foreign Affairs Minister during the 2017 Constituent Assembly election. After the elections were over, President Nicolás Maduro appointed former Vice President Jorge Arreaza as his successor, for which Moncada returned to exercise his functions as Vice Minister and Ambassador of Venezuela to the OAS.
Ambassador to OAS
In January 2019, the National Assembly of Venezuela appointed Gustavo Tarre Briceño as representative to the OAS, an international organization which does not recognize Nicolás Maduro as president. On April 9, 2019, the OAS voted 18 to 9, with six abstentions, to accept Tarre as the ambassador from Venezuela until new presidential elections can be held. The permanent council approved text saying "Nicolas Maduro's presidential authority lacks legitimacy and his designations for government posts, therefore, lack the necessary legitimacy." Antigua and Barbuda, Bolivia, Dominica, Grenada, Mexico, Saint Vincent and the Grenadines, Suriname, Uruguay and Venezuela voted against the change. Maduro's administration responded calling Tarre a "political usurper". According to the Washington Post, this acceptance undermines Maduro's presence internationally and marks a step in the official recognition of Guaidó's government. Voice of America called it an "historic vote". Tarre's appointment encouraged similar actions against the Maduro government by other international bodies. On April 10, 2019 the International Monetary Fundcut off Venezuelan access until a majority of its members recognized a Maduro or Guaidó representative, and the United States Vice PresidentMike Pence requested that the United Nations replace ongoing ambassador Samuel Moncada with a Guaidó-aligned one.