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 August 1971, the Bengali officers at the US Embassy formally announced their allegiance with the provisional Bangladesh Government.

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.