Answer
The primary opponent of Chad during Habré's rule was Libya. Libyan president Muammar Gaddafi supported several rebel groups in Chad in an effort to undermine Habré's government. In 1987, Libyan and Chadian forces fought a major battle at Fada, where the Chadian army defeated the Libyans. This victory ended the Libyan threat to Chad and solidified Habré's rule.