All nations put out pro-self propaganda.
Some nations have the resources and nouse to spread it via many social channels.
Just between Russia and the USA - which country delivers a shock result in elections?
Implication is: which country is the most aggressive and effective in influencing the respective results.
Not a conclusion, but a good place to put the priorities when looking for evidence. eg
Agressive? Ask Mr Litvinenko - er his widow perhaps.
Snowden might know, but could he tell you and live?