Karim had a brief teaching career at University of Dhaka. He joined the Pakistan Foreign Service in 1952. Karim served the Pakistani Missions in both
Calcutta and
New Delhi before assuming the key post of Director (India) in the Pakistan Foreign Ministry. In early 1970, Karim left Islamabad and took up the post of Counselor at the Pakistan Embassy in Washington DC. In the initial stage of
Bangladesh Liberation War, Karim propagated the cause of the independence of Bangladesh in the US diplomatic arena. But immediately afterwards Karim suffered two consecutive heart attacks within months and was hospitalized. In August 1971, the
Bengali officers at the US Embassy formally announced their allegiance with the provisional Bangladesh Government. Karim joined them, risking the well-being of his family, in spite of his poor health conditions.
Foreign Secretary After the independence of Bangladesh, Karim was nominated as the first Ambassador from Bangladesh to United States. But after a very short time, he was asked to assume the role of Foreign Secretary of Bangladesh. He also maintained international efforts to reconstruct war-ravaged Bangladesh under the UN Relief Operations, and to secure bilateral assistance from US and other major donors. His other major tasks were: reaching accords with New Delhi and Islamabad for the release of Pakistani POWs and war crime trial, repatriation of the stranded Bengalis from Pakistan and the Pakistanis from Bangladesh, and the distribution of assets and liabilities of the former federal government of Pakistan. ==Death and legacy==