As an agent of the Mossad LeAliyah Bet in the late 1940s and early 1950s, he arranged the mass airlift of Iraqi Jews to Israel known as Operation Ezra and Nehemiah.

[4] After graduating from the Herzliya Hebrew High School in Tel Aviv, he underwent agricultural training in kibbutz Degania Alef, and later Pardes Hana.

In 1945, Hillel and his colleagues worked at a Haganah munitions factory disguised as a laundry facility in the basement of the Ayalon Institute in Rehovot.

At that time, Iraqi Jews made aliyah to Israel through slow and treacherous overland routes facilitated by unreliable smugglers.

[9] Hillel visited Baghdad again in 1950 to negotiate the mass immigration of the Jews of Iraq, 120,000 of whom were airlifted to Israel in Operation Ezra and Nehemiah between 1950 and 1952.

While organizing pilgrimages to Mecca, Barnett met the director of a travel agency called Iraq Tours, Abdul Rahman Raouf.

In 1961 he became ambassador to the Côte d'Ivoire, Dahomey, Republic of Upper Volta, and Niger, before becoming a member of the Israeli Delegation to the United Nations between 1963 and 1967.