For an agency that's supposed to operate in secrecy, the Central Intelligence Agency makes headlines with ironic frequency. This time it's because of charges that the CIA a year ago produced for Nicaraguan rebels a handbook on how to subvert the Sandinista government through guerrilla tactics, including deception and violence against the government and its leaders.
The report raises a number of questions, which congressional committees are already preparing to try to answer. The first is whether the CIA did write the handbook; the Associated Press, which circulated the first report, says intelligence sources have confirmed the CIA role. President Reagan has rightly ordered an inquiry.
If further probing confirms this authorship, the questions get harder. The handbook says some Sandinista officials can be ''neutralized'' - often a euphemism for assassination - by guerrillas. Does this violate a 1981 presidential directive that in effect forbids American intelligence agencies from involvement in assassinations?
But the fundamental question is whether promotion of activities such as outlined in the handbook is the kind of activity that a democratic society like the United States can support.