Biden said during his meeting with leaders of the Jewish community at the White House: “I never really thought that I would see and have confirmed pictures of terrorists beheading children.”
The Washington Post quoted a White House spokesman as saying that neither President Biden nor any US official has independently seen any photos or verified reports on this. The spokesman added that Biden’s statements regarding the alleged atrocities were based on allegations by Israeli Prime Minister Benjamin Netanyahu’s spokesman and Israeli media reports.
Of course Biden saw no such imagery- the beheading claims are a play on old tropes. And Biden was merely spreading wartime propaganda to be hungrily gulped up by the true believers.