SAVAK (Persian: ساواک‎, short for سازمان اطلاعات و امنیت کشور Sāzemān-e Ettelā'āt va Amniyat-e Keshvar, literally "Organization of National Intelligence and Security of the Nation") was the secret police, domestic security and intelligence service of the Pahlavi dynasty. It was established by Iran's Mohammad Reza Shah with the help of the U.S. Central Intelligence Agency (CIA) and the Israeli MOSSAD. SAVAK operated from 1957 until the Iranian Revolution of 1979, when the prime minister Shapour Bakhtiar ordered its dissolution during the outbreak of Iranian Revolution. SAVAK has been described as Iran's "most hated and feared institution" prior to the revolution of 1979 because of its practice of torturing and executing opponents of the Pahlavi regime. At its peak, the organization had as many as 60,000 agents serving in its ranks according to one source, and another source by Gholam Reza Afkhami estimates SAVAK staffing at between 4,000 and 6,000.After the 1953 Iranian coup d'état, when the United States and the United Kingdom, removed Mohammad Mosaddeq, who was originally focused on nationalizing Iran's oil industry, but also set out to weaken the Shah from power on August 19, 1953. After the coup, the monarch, Mohammad Reza Shah, established an intelligence service with police powers. The Shah's goal was to strengthen his regime by placing political opponents under surveillance and repressing dissident movements. According to Encyclopædia Iranica:A U.S. Army colonel working for the CIA was sent to Persia in September 1953 to work with General Teymur Bakhtiar, who was appointed military governor of Tehran in December 1953 and immediately began to assemble the nucleus of a new intelligence organization. The U.S. Army colonel worked closely with Bakhtīār and his subordinates, commanding the new intelligence organization and training its members in basic intelligence techniques, such as surveillance and interrogation methods, the use of intelligence networks, and organizational security. This organization was the first modern, effective intelligence service to operate in Persia. Its main achievement occurred in September 1954, when it discovered and destroyed a large communist Tudeh Party network that had been established in the Persian armed forces.