General Zia-ul-Haq suspended Pakistan's constitution and instituted martial law after overthrowing Prime Minister Zulfikar Ali Bhutto in a 1977 coup. During his rule from 1977 to 1988, Zia introduced policies of Islamization, including stricter Islamic laws and increased emphasis on religion in education. He legitimized his power through a referendum and elections in 1985. Zia also strengthened Pakistan's ties with the U.S. and Saudi Arabia by supporting the mujahideen against the Soviet invasion of Afghanistan. However, his Islamization policies faced opposition, and unrest grew in Sindh and Balochistan. Zia ultimately died in a mysterious plane crash in 1988.