Sovereign nations are under no obligation to allow foreign governments to flood their communications systems with propaganda and harmful disinformation. Imagin

Sovereign nations are under no obligation to allow foreign governments to flood their communications systems with propaganda and harmful disinformation. Imagine if during during the cold war, the Soviet Union was permitted to flood NBC, ABC and half the newspapers in the US with demonstrably false and harmful political information. What would a reasonable public policy response to this be?