The tweets directly tied to Brexit were posted just after the vote in June 2016, but they're characterized as a "snapshot" that doesn't necessarily reflect the entire situation. Some of the ostensibly American accounts were unusually obsessed with Europe beforehand, however, and frequently posted similar anti-immigration and anti-Islam messages in response to terrorist attacks. A previous BuzzFeed study had identified 13,000 Twitter bots that supported leaving the EU, but it's not clear how many of those were tied to Russia.

The discovery isn't entirely shocking: if Russia was using Twitter bots to skew American sentiment, it wouldn't take much effort to do the same for Britons. Still, findings like this could be crucial to an official investigation into Russia's influence over Brexit. They also underscore how easy it can be to mount a modern propaganda campaign -- you can target audiences around the world with minimal effort.