most definitely since the Russian revolutions. IMO, one of the purposes of the New Deal and of the Great Society was to stave off the possibility of revolution.
Communists and socialists were among the first in modern times to espouse the ideas of racial equality, gender equality, the rights of workers and economic justice. As such they appealed to liberals and also threatened the same kinds of people who feel threatened by the left today.
The list from which Revoltin' Joe McCarthy worked initially was the one that the FBI prepared during World War II, when the Russians were our allies, at least in theory, and even before.
Then came the 1960s, including the Weathermen, including the bomb that Ayers planted in the Pentagon toilet. Back then, to the general public, that was an anti-war protest that many understood and some even admired. However, I doubt that the joint chiefs and others in government saw it that way. (Now, even to the general public, it's domestic terra-ism against the Homeland.)
The anti-Vietnam war/antidraft/peace movements, the peaceful civil rights movement, the more militant civil rights groups and the economic justice groups had begun to coalesce. A few assassinations and Kent State put a crimp in all that nonsense, to say the least, but the government got the message. Or rather, the message of the Russian revolutions got reinforced in the collective mind of the US plutocracy.
In any event, I am relatively certain they've been preparing for a revolution since well before World War II.*
911 was the perfect opportunity to ramp up even further with Homeland Security and the Patriot Act. Now, if I leave my building and walk eight blocks to the left, I will pass three cameras on the street and only heaven knows how many private security cameras, including the several that my own building operates.
*I have always believed that fear of a second revolution was the reason the nation got the Bill of Rights so fast (six months).
The people demanding this stuff had just fought and won a revolution against one form of government they did not care for and nothing prevented an encore. And, the serfs always outnumber the plutocrats. Voila! The bargaining power to demand and get the Bill of Rights and the willingness of government to fulfill its promise ASAP.