Query: What regime were Hussein loyalists part of?
Context: The insurgency, which included al-Qaeda affiliated groups, led to far more coalition casualties than the invasion. Other elements of the insurgency were led by fugitive members of President Hussein's Ba'ath regime, which included Iraqi nationalists and pan-Arabists. Many insurgency leaders are Islamists and claim to be fighting a religious war to reestablish the Islamic Caliphate of centuries past.