It has been widely claimed that J. Edgar Hoover stated, "Negro unity" was the greatest threat to the internal security of the United States.
However, there is no direct evidence that Hoover used this exact quote in this context.
What is known is that J. Edgar Hoover and the FBI, under his direction, had a history of surveilling, discrediting, and disrupting Black civil rights organizations and leaders through programs like COINTELPRO.