As we all know by now, EPCOT Center wasn’t exactly what Walt described when he spoke of EPCOT. Had it been built, his utopian “Community of Tomorrow” surely would have raised a few eyebrows. But it seems that the park that did eventually open was still concerning for some people, namely the Federal Bureau of Investigation.
According to MuckRock, recently released FBI documents indicate that the agency was not only worried about the communist influence of World Showcase but also feared that terrorist groups from the real countries portrayed in Epcot would attack the theme park.
A couple of years before the park opened, the Soviet Union was apparently in talks to join World Showcase. FBI documents suggest that part of the reason this never happened was because the Union was informed they wouldn’t be allowed to use their pavilion to make political statements.
Although the Soviets never joined EPCOT, another communist nation did: The Peoples Republic of China. The documents show that the Burea was especially interested in the Cast Members who would be working at China pavilion. (Note the use of the term “circle vision” in the middle of a paragraph discussing how many Chinese employees would be staffing the pavilion):
Apparently the first Cast Members chosen to work at the pavilion were already living in America and attending various colleges. Take a look at how much detail the FBI knew about one of these Cast Members: 
While these are some of the most intriguing passages, there’s still plenty more on what the FBI thought about World Showcase and EPCOT that you can ready for yourself here.