Why is the Truman administration often credited with (or blamed for) creating a "national security state" in the late 1940s?

In 1947, Secretary of State George C. Marshall devised the European Recovery Program (or Marshall Plan), to help rebuild European nations and economies after the devastation of World War II. Among other goals, the Marshall Plan was designed to speed Europe's economic recovery, so that European nations would be less vulnerable to communist influence within and from the USSR. The Marshall Plan even offered money to the USSR and the nations of Eastern Europe, but these countries declined American assistance. The U.S. spent some 13 billion dollars under the Marshall Plan.

In March 1947, the administration of President Harry S. Truman declared that the U.S. would supply economic and military aid to any nation that was threatened by communism. This Truman Doctrine differed from George Kennan's view of containment, which focused on containing the USSR, but did not advocate fighting communism wherever it might arise. The Truman Doctrine committed the U.S. to a policy of global containment.

In order to direct American Cold War policy, the Truman administration proposed the National Security Act (1947). This law created the Department of Defense (which had previously been called the War Department), the National Security Council (NSC), and the Central Intelligence Agency (CIA). The NSC linked the administration's military and diplomatic advisors, while the CIA was created to gather information about the Soviet Union and other nations considered hostile to the United States. The Truman administration, with Congressional approval, also increased American defense spending, which had shrunk after World War II.