Diplomacy: Theory and Practice, 6th ed.  –  Online updating pages

Chapter 13: Public Diplomacy

p. 215, lines 7–8 up, the mendacity (lying) of crude propaganda: It’s worth drawing attention here to one of propaganda’s most effective devices because it is currently being employed to help justify Putin’s war against Ukraine. This is the ‘big lie’ (aka outrageous ‘disinformation’); that is, a false claim that is so startling that it encourages the conclusion that no-one would be so brazen as to advance it unless it were true. Putin’s claims that Ukraine is not a ‘country’ and is in any case run by ‘neo-Nazis’ are classic examples of the ‘big lie’, as is Donald Trump’s allegation that the Democrats ‘stole’ the last presidential election. The trick is to blow up out of all proportion any scrap of evidence (e.g. Ukraine’s Azov Regiment) that might support the big lie and repeat it endlessly. Autocracies, of course, find it much easier to employ the big lie because they suffer no domestic challenges to their propaganda. Wikipedia has a useful entry on the device.

Further reading
EU External Action Service, 1st EEAS Report on Foreign Information Manipulation and Interference Threats: Towards a framework for networked defence, February 2023

Scott, Mark, ‘Russia turns its diplomats into disinformation warriors’, Politico, 7 April 2022