The post of DCI was established by President Harry Truman on January 23, 1946, with Admiral Sidney Souers being the first DCI, followed by General Hoyt Vandenberg who served as DCI from June 1946 to May 1947. The DCI then ran the Central Intelligence Group (CIG), a predecessor of the CIA. The office of DCI thus predates the establishment of the Central Intelligence Agency. The CIA was created by the National Security Act of 1947, which formally defined the duties of the Director of Central Intelligence. This 1947 Act also created the National Security Council.