The passage of the National Security Act of 1947 was a restructuring of the United States military to better support the security of Americans. President Truman signed the act into law, inspired by the success of the Office of Strategic Services throughout World War II. OSS was dissolved after the war ended, but its operations continued in the Departments of State and War.
Truman had heard a proposal from William Donovan, the OSS creator, to create an organization in charge of procuring intelligence and conduct covert operations. Donovan proposed the creation of a civilian agency that is centralized, with the authority to conduct operations abroad. At the time, Donovan was careful to state that the fledgling CIA should not have powers of police at home or abroad, it would be a vessel for reporting and accumulating intelligence.
The first director of the CIA was Rear Admiral Roscoe H. Hillenkoetter. He oversaw operations in support of Christian democrats in Italy. The CIA quickly began a program of plausible deniability, or setting operations up such that other nations could not truly uncover who was behind the plot.
The program descended further into secrecy in 1949, when it was given authorization to hide its employee’s names, salary information, official titles and job functions from public scrutiny.
Today, under increased pressure for transparency, the organization uses something called Open Source Intelligence to provide maps and documentation for the public and the intelligence community.