Amid clashes between right-wing demonstrators and anti-fascist counter-protesters on June 29, 2019, Portland police issued a troubling tweet stating that they had “received information that some of the milkshakes thrown today during the demonstration contained quick-drying cement”:

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

The tweet’s substance was a bit of salacious information that spread far and wide, playing off a trend begun in the U.K. of tossing milkshake drinks at far-right politicians. Multiple news outlets took the word of police at face value and ran with the story, even though no evidence was provided to support it.

We sent the Portland Police Bureau a request for comment, to which Lt. Tina Jones stated that she was “unable to provide comment” about ongoing investigations. Jones did not reply to our follow-up questions for further information and an interview.

However, Portland city officials admitted in a July 1, 2019, phone call with reporters that the evidence for the statement made in the tweet was based solely on an observation of a police lieutenant in the field that day who, according to the Portland Mercury, “‘saw a powdery substance that appeared to cause some irritation [when in contact with skin].’ The lieutenant also said the milkshake smelled similar to wet concrete, a smell they were familiar with from ‘having worked with concrete before.'”

The police department’s tweet referenced vegan milkshakes made and distributed by the activist group Popular Mobilization (PopMob).

“They put targets on our backs,” said Popular Mobilization spokeswoman Effie Baum, who asserted that activists didn’t add cement or any other non-food ingredient to the drinks and were “flabbergasted” at how the rumor spread online. Baum said the group has been receiving a bevy of threats as a result of the tweet:

“At first we were like, ‘are you kidding me, this is completely ridiculous,'” Baum told us. “Watching it unfold in real time it started with police saying there might have been cement milkshakes to some people saying there was acid. Then it became, the milkshakes were solid cement. It just went completely off the rails very quickly.”

The only evidence offered for the rumor was a “recipe” sent anonymously to police after the tweet was published.

Alex Zielinkski, news editor for the Portland Mercury, told us the claim that any of the milkshakes contained cement appeared to be nothing more than a likely hoax. She arrived early to see PopMob activists distributing milkshakes to friends and supporters, who then drank them.

“There was nothing I saw that gave me any suspicion that it was anything other than a milkshake,” Zielinski told us. PopMob activists were serving the pre-made drinks out of large containers and pouring them into 12-ounce coffee cups, then distributing them. “It didn’t raise any red flags.”

Zielinski added that no response from the police or any other city department that day indicated a foreign substance was being added to drinks being distributed en masse to counter-demonstrators. She said she saw at least two people toss the liquid from their cups at rivals, but didn’t notice anything that raised alarm about the substance.

The misinformation was perpetuated by “national media outlets that don’t have the kind of resources on the ground in Portland to understand the nuance or the basic facts. I know every local reporter in the country has that frustration,” Zielinski told us. “There’s only so much you can do to stop that.”

The police department’s tweet was sharply criticized by academic observers, including former FBI agent and New York University professor Michael German, who told Williamette Week it played “into the hands of the far-right provocateurs who have been trying to present a resistance to their activities as more dangerous than they are.”

Stanislav Vysotsky, an assistant professor of sociology and criminology at the University of Wisconsin at Whitewater, told us a long history of animosity exists between Portland police and left-wing activists, and the “cement milkshake” affair did little towards ameliorating that.

“[The police department’s] public actions have been that they are willing to mobilize against anti-fascists in a way that they aren’t against the right,” Vysotsky told us. “It’s been interesting to see that despite the criticism they’ve received, there hasn’t really been any proactive attempt to address that. I understand it’s complicated, but doing things like putting out a patently false claim about cement milkshakes doesn’t help to bridge the chasm. It only helps to build that distrust, to build that kind of tension.”