The deadliest antisemitic attack in United States history took place on October 27, 2018 when a gunman opened fire on the Tree of Life Synagogue congregation in Pittsburgh, Pennsylvania. Eleven people were murdered and seven more were injured. On August 2, 2023, a federal grand jury unanimously recommended the death sentence after finding the gunman guilty on 63 counts.

In the time since the attack, the shooter’s white supremacist convictions, fanatical hatred of Jews, extremist online activity, and influence on extreme-right communities have been revealed. The International Centre for the Study of Radicalisation (ICSR) and the Program on Extremism at George Washington University released a report, Imagined Threats: Demographic Conspiracy Theories, Antisemitism, and the Legacy of the 2018 Pittsburgh Synagogue Attack, which explores the ideological foundations behind the violent attack on the Jewish community and the unfortunate legacy it has spawned in extreme-right communities online. The report examines the history of Western demographic conspiracy theories and how they manifest today, the demographic conspiracy theories embraced by the Pittsburgh gunman, the impact the Pittsburgh Synagogue attack has had in inspiring subsequent terrorist attacks, and the glorification of the gunman in online extreme-right communities.

For further related reading, visit the HSDL In Focus topics on Hate and Antisemitism, Online Extremism, and Security in Places of Worship or the HSDL Timeline event for October 27, 2018.