Russian spies hired an ex-US marine to spread fake news aimed at smearing the Harris campaign that likely included rumours Tim Walz groped his former students.

John Mark Dougan, a former county sheriff’s deputy in Florida, is working directly with Russian military intelligence to meddle in the US elections, according to documents obtained by European intelligence.

The files, seen by The Washington Post, show how Mr Dougan, a serial Kremlin propagandist, has received help and funding from the GRU to turn his fake news sites into one of the most formidable sources of misinformation targeting US voters in recent months.

His network is believed to be responsible for a recent AI-generated video smearing Mr Walz, the Democratic vice-presidential candidate, which received five million views in 24 hours on X, formerly Twitter, and which US officials said was created by Russia.