The challenges for democracies and open societies in the misinformation age substantially outstrip those faced by authoritarian regimes. This is most prominently because of their more limited range of response options in the context of public accountability. A prominent obstacle in American domestic misinformation defenses is that they can easily veer into the political; and we want neither the military involved in domestic affairs nor the government taking sides in political disputes.
In the context of these crucial American values, the response space for US government defenders is extremely narrow. In this context–and additional factors specific to this administration–the Department of Homeland Security released an outstanding primer about online misinformation in June.