It sounds like the ramblings of a paranoid crank. And that’s exactly what it is, except the crank in question was J. Edgar Hoover, head of the Federal Bureau of Investigation, in a 1950 letter to the White House. The proposed plan was very real, and the letter describing it was declassified in December. It can be found in the latest volume of The Foreign Relations of the United States, a series published by the U.S. State Department, and it can be downloaded at state.gov/r/pa/ho/frus/truman/c24687.htm.
There’s no evidence that the Truman White House took Hoover’s proposal seriously. Interestingly, a decade earlier, when the previous president supported a different plan to round up Americans without regard for due process, Hoover had argued for their civil liberties. Those internees were Japanese Americans imprisoned during World War II, and Hoover’s protests were ignored.