Given the task definition and input, reply with output. Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: For many years, Sudan had an Islamist regime under the leadership of Hassan al-Turabi. His National Islamic Front first gained influence when strongman General Gaafar al-Nimeiry invited members to serve in his government in 1979. Turabi built a powerful economic base with money from foreign Islamist banking systems, especially those linked with Saudi Arabia. He also recruited and built a cadre of influential loyalists by placing sympathetic students in the university and military academy while serving as minister of education. Question: Who was the leader of the Islamist regime in Sudan?
Hassan al-Turabi