In the 1980s he led the Democratic Revolutionary Council (in French CDR: Conseil Démocratique Révolutionnaire), a military-political group opposing the government of President Hissène Habré.

He held several cabinet positions within the GUNT (Chad National Union Government; in French, "Gouvernement d'Union Nationale du Tchad"), led by Goukouni Weddeye (or Oueddei).

In November 1984, Acheikh Ibn-Oumar was arrested in Tripoli and then transferred to Tibesti where he remained in detention until December 1985, because of serious divergences with both late Colonel Gaddafi and Goukouni.

[3][4][5] In defeat Acheikh Ibn Oumar distributed 1,500 automatic weapons to his Arab allies in Chad and "across the international boundary in Darfur.

As Minister of Foreign Affairs, Ibn-Oumar was the Chadian representative in Algiers for the 31 May 1989 effort at peaceful resolution of the dispute with Libya over the Aozou Strip.