Rumours spread like wildfire on social media last weekend after clashes between far-right demonstrators and counter-protesters in Portland, Ore., spilled over into violence and left conservative writer Andy Ngo with facial injuries. On Twitter, prominent media figures accused protesters associated with antifa — shorthand for antifascist or antifascism — of throwing milkshakes laced with a cement-like substance, while other users shared photos of what they claimed were bystanders who had suffered chemical burns from being hit with milkshakes. Before long, these claims made their way onto the pages of mainstream newspapers and were reported as fact on television by outlets such as CNN.

The problem? Many of those claims weren't true, and others are still nothing more than unsubstantiated rumours. The allegations are just the latest effort by far-right activists to vilify the antifascist movement, serving as a cautionary tale for media outlets who often uncritically accept these deceptive narratives and pass them along as fact. The origins of a disinformation campaign Most of the distorted, misleading and false claims about the events in Portland stem from a single tweet sent by the Portland Police Bureau (PPB) on Saturday, stating that officers had "received information that some of the milkshakes thrown today ... contained quick-drying cement." PPB did not state where that information came from or whether it had been confirmed.

While there is video evidence of people drinking and throwing milkshakes, the "quick-drying cement" claims remain unsubstantiated at this point. National Observer reached out to Portland police for clarification, but the bureau has not responded to our inquiries. Police have received information that some of the milkshakes thrown today during the demonstration contained quick-drying cement. We are encouraging anyone hit with a substance today to report it to police. — Portland Police (@PortlandPolice) June 29, 2019 Portland police did respond to an inquiry from Willamette Week's Katie Shepherd, telling her they had "received information during the event that some people were mixing a concrete-like substance into the milkshakes" and that a police lieutenant observed a cup that "appeared to have material on it consistent with quick drying cement." However, they did not confirm the information they shared in the initial tweet. https://twitter.com/katemshepherd/status/1145492073224650753 The Portland Mercury received similar information from a Portland police spokesperson, who told the local paper they "put out the tweet to bring attention to this potential hazard and to encourage people to contact us if they were the victim of a crime." "It appears that one officer's recognition that a coconut milkshake looks a little like wet cement convinced PPB to issue the worrisome tweet," the Portland Mercury concluded, citing information from the PPB spokesperson and social media posts from people who drank the milkshakes and did not get sick or otherwise suffer injuries.

The rumours spread like wildfire PPB's tweet created a firestorm, leading to a flood of baseless, deceptive and, in some cases, completely fabricated claims, with some social media users even asserting that antifa had carried out "acid attacks." Former Rebel Media employee Jack Posobiec, who currently works for right-wing outlet One America News Network, was among the first and most vocal Twitter users pushing the unsubstantiated rumors about "concrete milkshakes" as fact.