This tactic consists in promoting a determined narrative by means of implicit assumptions rather than explicit statements.
This works because the human mind tends to be focused on what's openly stated rather than just implied; therefore the latter are much more able to bypass rational scrutiny unless they're already known to be false. For this reason, propaganda works at its best when the message to convey is hidden between the lines of other tangentially related (or even completely unrelated) subjects; this is done in various ways, like: conveying the message through subordinate clauses rather than main ones, making profuse use of strongly loaded language, making quick passing remarks while talking about other stuff, making statements based on the premise that the message to convey is already true without explicitly saying it, and so on...
People who are already aware that the message to convey is false are mostly unaffected by this, but as for people with no pre-existing opinions on the subject, by saturating the media and public dialogue with such tricks, a very detailed pre-conceived narrative can be slowly and subconsciously implanted into their minds without any need to support it with any kind of evidence or argument.
Moreover, in case anyone notices the trick and butts in to reply, they can be quickly dismissed by accusing them of being "too sensitive to criticism" or trying to "derail the conversation".