On June 8, 1998, General Sani Abacha, the military leader who took power in Nigeria in 1993, died of a reported heart attack and was replaced by General Abdulsalam Abubakar. General Abubakar released political prisoners and initiated political, economic, and social reforms. Relations between the United States and Nigeria improved with the subsequent transfer of power to a civilian government. Nigeria continues to make progress in strengthening its fragile democracy but faces serious economic challenges. Nigeria remains relatively stable, although ethnic and religious clashes in some parts of the country have led to massive displacement of civilian populations.