Afghanistan's political order began to break down with the overthrow of King Zahir Shah by his cousin Mohammed Daoud Khan in a bloodless 1973 coup. Daoud Khan had served as prime minister since 1953 and promoted economic modernization, emancipation of women, and Pashtun nationalism. This was threatening to neighboring Pakistan, faced with its own restive Pashtun population. In the mid-1970s, Pakistani Prime Minister Zulfikar Ali Bhutto began to encourage Afghan Islamic leaders, such as Burhanuddin Rabbani and Gulbuddin Hekmatyar, to fight against the regime. In 1978, Daoud Khan was killed in a coup by Afghan's Communist Party, his former partner in government, known as the People's Democratic Party of Afghanistan (PDPA). The PDPA pushed for a socialist transformation by abolishing arranged marriages, promoting mass literacy and reforming land ownership. This undermined the traditional tribal order and provoked opposition from Islamic leaders across rural areas, but it was particularly the PDPA's crackdown that contributed to open rebellion, including Ismail Khan's Herat Uprising. The PDPA was beset by internal leadership differences and was weakened by an internal coup on September 11, 1979, when Hafizullah Amin ousted Nur Muhammad Taraki. The Soviet Union, sensing PDPA weakness, intervened militarily three months later, to depose Amin and install another PDPA faction led by Babrak Karmal.