This post has been updated with the White House's comment.

President Trump has returned to the controversial — and unproven — claim that arguably launched his 2016 campaign, accusing migrants headed for the United States of epidemic rape and the countries they come from of sending criminals northward.

On Thursday in West Virginia, Trump addressed the so-called migrant “caravan” that he has been tweeting and warning about for days.

“They're not putting their good ones,” Trump said. “And remember my opening remarks at Trump Tower when I opened. Everybody said, 'Oh, he was so tough.' And I used the word 'rape.' And yesterday it came out where, this journey coming up, women are raped at levels that nobody has ever seen before. They don't want to mention that.”

As with Trump's claim in June 2015, there is almost no actual evidence on which to base this claim. It's not clear what Trump means by “yesterday it came out,” given there don't appear to be any mainstream news reports of a rape epidemic taking place in the caravan. The only mentions of rape with regard to the caravan in recent days, in fact, refer to criminal behavior that the migrants have been trying to escape in their home countries or along the route.

The Center for Public Integrity reported Wednesday, “The path to asylum isn’t easy: If they’re able to enter and pass that initial test in a quest for asylum, migrants must then attempt to convince U.S. officials they face mortal danger — often because of extortion, attempted recruitment, rape and death threats....”

A Los Angeles Times report this week, meanwhile, noted how the such migrants often fall victim to such crimes — but with rapes committed by people they encounter along the way, rather than by one another:

Similar caravans have been organized other years around Easter by a group called Pueblos Sin Fronteras .... The caravans are designed to bring awareness to the conditions that have prompted many people to flee Central America, as well as the dangers migrants face once they're on the road.

Robberies, rapes and assaults — perpetrated by smugglers, drug cartel members and Mexican immigration agents — are common. In one incident in 2010, 72 kidnapped migrants were killed by a cartel in northern Mexico.

And sure enough, the White House is pointing to such reports. Asked about Trump's claim, an official shared a 2014 link to a story about how many Central American women and girls are raped on the way to the United States. This does not address Trump's claim that something came out "yesterday," though, and it ignores the fact that Trump was referring to the migrants themselves as being dangerous criminals.

Whatever Trump was referring to about the caravan, others who have witnessed it firsthand say they've seen no such thing. A reporter for BuzzFeed News who has been following the caravan for almost two weeks tweeted Thursday that he has heard of no such rash of rapes.

It appears to be the third distinct time that Trump has accused migrants of a rape epidemic. The first was in his announcement speech when he suggested that large percentages of illegal immigrants in the United States are criminals who commit crimes including rape. In the middle of the 2016 campaign, he also referred to refugees working their way through Europe as having unleashed a torrent of rapes upon countries such as Germany.

The evidence for Trump's claim that illegal immigrants disproportionately committed rape, in particular, was specious. Undocumented immigrant crime is actually lower, per capita, even as horrific incidents do exist and have been regularly invoked as anecdotes.

Unless Trump has some information the rest of us don't about this epidemic in the caravan, though, it seems he is spreading conspiracy theories again.