Everyone uses them.
Such tactics include slander, defamation, threats, getting close to disaffected or minimally committed fellow activists to persuade them (via psychological tactics described above) to turn against the movement and give false testimony against their former compatriots. They will plant illegal substances on the activist and set up an arrest; they will plant false information and set up “exposure,” they will send incriminating letters [emails] in the name of the activist; and more; they will do whatever society will allow.
The FBI counterintelligence program’s stated purpose: To expose, disrupt, misdirect, discredit, and otherwise neutralize individuals who the FBI categorize as opposed to the National Interests. “National Security” means the FBI’s security from the people ever finding out the vicious things it does in violation of people’s civil liberties. The FBI can use their size and power to basically scare people into follow the law.