The following document details how to deal with all of the “conspiracies” on the assassination of JFK.
It looks like the same strategies are still used in 2019 (on a wide area of topics).

3. Action. We do not recommend that discussion of the assassination question be initiated where it is not already taking place. Where discussion is active [business] addresses are requested:
a. To discuss the publicity problem with [?] and friendly elite contacts (especially politicians and editors), pointing out that the Warren Commission made as thorough an investigation as humanly possible, that the charges of the critics are without serious foundation, and that further speculative discussion only plays into the hands of the opposition. Point out also that parts of the conspiracy talk appear to be deliberately generated by Communist propagandists. Urge them to use their influence to discourage unfounded and irresponsible speculation.
b. To employ propaganda assets to [negate] and refute the attacks of the critics. Book reviews and feature articles are particularly appropriate for this purpose. The unclassified attachments to this guidance should provide useful background material for passing to assets. Our ploy should point out, as applicable, that the critics are (I) wedded to theories adopted before the evidence was in, (I) politically interested, (III) financially interested, (IV) hasty and inaccurate in their research, or (V) infatuated with their own theories. In the course of discussions of the whole phenomenon of criticism, a useful strategy may be to single out Epstein's theory for attack, using the attached Fletcher [?] article and Spectator piece for background. (Although Mark Lane's book is much less convincing that Epstein's and comes off badly where confronted by knowledgeable critics, it is also much more difficult to answer as a whole, as one becomes lost in a morass of unrelated details.)

4. In private to media discussions not directed at any particular writer, or in attacking publications which may be yet forthcoming, the following arguments should be useful:
(...)
c. Conspiracy on the large scale often suggested would be impossible to conceal in the United States, esp. since informants could expect to receive large royalties, etc. Note that Robert Kennedy, Attorney General at the time and John F. Kennedy's brother, would be the last man to overlook or conceal any conspiracy. And as one reviewer pointed out, Congressman Gerald R. Ford would hardly have held his tongue for the sake of the Democratic administration, and Sensator Russell would have had every political interest in exposing any misdeeds on the part of Chief Justice Warren. A conspirator moreover would hardly choose a location for a shooting where so much depended on conditions beyond his control: the route, the speed of the cars, the moving target, the risk that the assassin would be discovered. A group of wealthy conspirators could have arranged much more secure conditions.
http://www.jfklancer.com/CIA.html