Nauclér served as chief adviser to the Ethiopian Kagnew Battalion during the Korean War from 1951 to 1952 and as Ethiopian consul and head of the Ethiopian Liaison Section at the UN Commander in Chief General Matthew Ridgway's headquarters in Tokyo from 1951 to 1952. After his tour in Korea, Nauclér returned to Sweden. In 1956 he was appointed major and chief of Section III and the staff company of the Swedish UN Battalion I in Egypt. Nauclér was also head of the Swedish monitoring police at the Suez Canal in the aftermath of the Suez Crisis in 1957 and he was promoted to major in the Swedish Army in 1959. Nauclér was colonel and commander of the Swedish UN Battalion XVI K in Congo during the Congo Crisis from May 1962 to October 1962 and he was sector commander in Katanga in 1962. Back in Sweden again, he was commander of the National Home Guard Combat School from 1957 to 1963 when he retired from military service. From 1963, Nauclér was chief of staff in Yekepa, Liberia for the mining corporation Lamco. A few years later he led the International Red Cross team in Biafra during the Biafran War. In the 1970s, Nauclér worked for the Red Cross in Zambia. He served in the Red Cross Associations' Secretariat in Geneva and as the Red Cross's chief delegate in Uganda. He was the Red Cross's chief delegate in Ethiopia in 1974 and the Swedish Red Cross representative in The Gambia in 1974-75. The last Red Cross mission in Uganda in 1981 nearly cost him his life. His heart was failing and he had to return home.