The video falsely claiming that the United States Agency for International Development paid Ben Stiller, Angelina Jolie and other actors millions of dollars to travel to Ukraine appeared to be a clip from E!News, though it never appeared on the entertainment channel.

In fact, the video first surfaced on X in a post from an account that researchers have said spreads Russian disinformation.

Within hours it drew the attention of Elon Musk, who reposted it. So did President Trump’s son Donald Trump Jr.

They amplified the false video as Mr. Musk pressed a crusade to shut down U.S.A.I.D., the agency that has distributed much of the government’s foreign aid since 1961. Working with Mr. Trump’s blessing as the head of a government efficiency campaign, Mr. Musk and others in the administration have taken over the agency’s headquarters, frozen grants and notified employees that nearly all of them will be laid off.

The dismantling of the agency has been accompanied by a torrent of anger online from right-wing influencers and accounts that are promoting false claims and conspiratorial thinking.

While some politicians and voters have long questioned the value of foreign aid, those attacking the agency have often distorted facts and, wittingly or unwittingly, embraced as true anything that could help justify targeting U.S.A.I.D.