Ambassador Trezza chaired the Missile Technology Control Regime, the Conference on Disarmament in Geneva and the UN Secretary General's Advisory Board on Disarmament Matters in New York. He was Italy's Ambassador for Disarmament and Non-Proliferation, and Ambassador to the Republic of Korea. He coordinates the Italian ELN (European Leadership Network) group.
Carlo Trezza joined the Italian Foreign Service in 1970, serving in Zambia, Israel and Germany, before returning in 1981 to Rome to work in the Ministry of Foreign Affairs Political Department. In 1984, he was posted to Madrid as the First Counsellor. In 1989 he became the Head of the Press and Information Section of the Embassy of Italy in Washington, DC, a post he held for three years. From 1992 until 1996, he served as Head of the European Security and Disarmament Department of the Ministry of Foreign Affairs in Rome, followed by a year in the Office of the Secretary General of the Ministry of Foreign Affairs.