Agents of the Soviet Union were motivated, active and probably embedded in a more widespread fashion than we can fathom.
That's what makes the irresponsible incompetent blundering of amateur politicians looking for an angle all the more deplorable. They not only distracted from efforts to effectively counter-act genuine threats, they discredited the motivation for such efforts altogether.
The freaking "Red Scare" was so badly distorted in its fury, it deprived our leadership of access to a lot of experienced academics, and that alone cost goodness knows how many thousands and thousands of lives, just from the utter blindness we charged into Vietnam with for starters.