The reports circulated like wildfire: fliers surfacing in the eastern Ukrainian town of Donetsk ordering Jews there to register with the local government or face deportation.
U.S. officials quickly condemned the leaflets, with Secretary of State John Kerry mentioning it at the beginning of his remarks in Geneva, Switzerland, after emerging from an eight-hour meeting on the situation in Ukraine.
There is a concerted disinformation campaign going on with all sides of the conflict trying to paint the other as extreme. But it's not clear where the leaflets came from and how many were distributed. Still, the reports raised an outcry.
"This is not just intolerable, it's grotesque. It's beyond unacceptable. And any of the people who engaged in these kinds of activities, from whatever party or ideology or whatever place they crawled out of, there is no place for that," Kerry said.
The U.S. ambassador to Ukraine, Geoffrey Pyatt, added on CNN, "It's chilling. I was disgusted by these leaflets."
"Reports of Jews being forced to register by pro-Russian forces in Eastern Ukraine are chilling, outrageous and must be universally condemned," Ben Rhodes, the president's deputy national security adviser, tweeted.
The Russian government has previously floated the specter of anti-Semitism in eastern Ukraine and Crimea as one of the reasons why its intervention in the region was necessary. And there have also been isolated incidents of various types of religious intolerance throughout Ukraine.
"I don't have more details on where the leaflets are coming from, but I know we're looking into it," State Department deputy spokesperson Marie Harf said shortly after Kerry spoke,adding that the United States would take any instance of anti-Semitism in Ukraine seriously even if, as one reporter put it, "it turned out that it's just some dude running around with mimeograph machine throwing these leaflets around."
Representatives of three separate Jewish organizations in Donetsk told ABC News that they didn't even know whether the flyers existed beyond images that appeared on news sites, including on USA Today.
"Just let us live normally, we live normally, we have a normal life," an exasperated member of one of the Jewish groups said.
Reporters from the Daily Beast visited the room in the government building where Jews were told by the pamphlet to go to register, and found it empty.
Even still, rumors of the leaflets were enough to elicit responses from members of Congress, like Rep. Nita Lowey, D-N.Y.
"I urge you to do everything possible to ensure that Jewish and other minority communities throughout the country are protected from any form of prejudice," Lowey wrote in a letter to Kerry.
And the word "Jews" quickly became a trending topic on Twitter.
But even if the flyers do not represent the official policy of what pro-Russian activists now call the "Donetsk People's Republic," U.S. government officials and Jewish groups remained vocal in their condemnation of anti-Semitism in any form, organized or otherwise.
"The ADL today condemned the appearance of anti-Semitic fliers in Donetsk, Ukraine, and called on all parties involved in the political conflicts in Ukraine to refrain from 'cynical and politically manipulative' exploitation of anti-Semitism," said Abraham H. Foxman, ADL National Director, in a statement to Mashable.
"We are skeptical about the flier's authenticity, but the instructions clearly recall the Nazi era and have the effect of intimidating the local Jewish community," he said.
Alexander Marquardt, Dada Jovanovic and Dennis Powell contributed to this report.