Following the June–October 1997 civil war, Opimbat, who was President of the Congolese Association for Openness, Salvation and Solidarity (ACOSS), was appointed to the government as Minister of National Solidarity, the Displaced and the Victims of War, in charge of Humanitarian Action, on 2 November 1997. He was subsequently moved to the post of Minister of Health, Solidarity, and Humanitarian Action on 12 January 1999.