The Americans who pushed a conspiracy theory the night of the Iowa caucuses have migrated to coronavirus conspiracies on Twitter, with help from a very Russia-friendly account.

By Nicole Perlroth @ NYTimes.com, June 15

The night of the Iowa caucuses in February, Robby Mook, Hillary Clinton’s 2016 campaign manager, logged into Twitter to find the hashtag #RobbyMookCaucusApp trending across the country. Pundits on both sides of the aisle accused him of developing a mobile app to rig the Democratic primary against Senator Bernie Sanders.

Soon his phone was buzzing with calls from reporters demanding to know what role he had played in creating the app, a flawed vote-reporting system that delayed caucus results for days.

But he had never even heard of the app, which was developed by a company called Shadow Inc. This mattered little to the thousands of Twitter users attacking him online. Four months later, Mr. Mook said with a sigh, “There are still people out there who believe I developed that app.”

Mr. Mook was the target of an American-made social media conspiracy theory that was picked up by Americans and quickly amplified by accounts with Russian links. What happened to him in February — though just a sliver of the enormous amounts of misinformation pouring onto social media platforms — offers a manual to understand how false information about the coronavirus and the election is now spreading [....]