What is a National Security State, and why did the US create one after WWII?

A National Security State is a government in which the military has significant power and influence over not only military affairs, but economic and political affairs as well. In a National Security State, the military is considered the top priority of the government and receives an extremely high portion of the budget. We can see that following World War II, America spent significantly more money on defense and opened military bases around the world, particularly in countries that had been defeated in WWII (most notably Germany and Japan, where many American military bases remain to this day). Prior to this, America had been spending significantly more money on social programs via the New Deal, which reflects the shift in the priorities of the American government.
It can be said that America officially became a national security state in 1947 when President Truman enacted the National Security Act of 1947. This was done to uphold the Truman Doctrine, which was America's response to the Soviet Union and the spread of communism around the world. In other words, America became a national security state during the Cold War to fight communism and reduce the influence of the Soviet Union around the world while, at the same time, increasing its own influence worldwide. The National Security Act of 1947 also created the Central Intelligence Agency (CIA) and Department of Defense (DoD) which are major institutions that uphold America as a national security state and still exist today.
http://pages.ucsd.edu/~dmares/National%20Security%20State.pdf

https://history.state.gov/milestones/1945-1952/truman-doctrine