How has the American sense of security changed the various definitions of freedom in American life from WWII to the War on Terror?
In general, the more that Americans feel like they are in danger, the more they are willing to define freedom in a more restrictive way. This has happened on at least two occasions since the end of WWII.
First, Americans were willing to define the freedoms of speech and association in a more restrictive way during the earlier parts of the Cold War. They restricted these freedoms because they feared that the freedoms would be used to promote communism.
Second, during the War on Terror, Americans have defined the freedom of religion and the freedom from unwarranted searches and seizures more restrictively. They have feared that these freedoms would be used to promote radical Islam and to plan terrorist attacks. Therefore, they have been willing to see them curtailed.
In these ways, we have tended to define freedom in a much more restricted fashion when we fear those freedoms might be used to hurt us.