WASHINGTON — It was the kind of story destined to take a dark turn through the conservative news media and grab President Trump's attention: A vast horde of migrants was making its way through Mexico toward the United States, and no one was stopping them.
"Mysterious group deploys 'caravan' of illegal aliens headed for U.S. border," warned Frontpage Mag, a site run by David Horowitz, a conservative commentator.
The Gateway Pundit, a website that was most recently in the news for spreading conspiracies about the school shooting in Parkland, Fla., suggested the real reason the migrants were trying to enter the United States was to collect social welfare benefits.
And as the president often does when immigration is at issue, he saw a reason for Americans to be afraid. "Getting more dangerous. 'Caravans' coming," a Twitter post from Mr. Trump read.
The story of "the caravan" followed an arc similar to many events — whether real, embellished or entirely imagined — involving refugees and migrants that have roused intense suspicion and outrage on the right. The coverage tends to play on the fears that hiding among mass groups of immigrants are many criminals, vectors of disease and agents of terror. And often the president, who announced his candidacy by blaming Mexico for sending rapists and drug dealers into the United States, acts as an accelerant to the hysteria.
The sensationalization of this story and others like it seems to serve a common purpose for Mr. Trump and other immigration hard-liners: to highlight the twin dangers of freely roving migrants — especially those from Muslim countries — and lax immigration laws that grant them easy entry into Western nations.
The narrative on the right this week, for example, mostly omitted that many people in the caravan planned to resettle in Mexico, not the United States. And it ignored how many of those who did intend to come here would probably go through the legal process of requesting asylum at a border checkpoint — something miles of new wall and battalions of additional border patrol would not have stopped.
"They end up in schools on Long Island, some of which are MS-13!" declared Brian Kilmeade on the president's preferred morning news program, "Fox & Friends," referring to the predominantly Central American gang.
The coverage became so distorted that it prompted a reporter for Breitbart News who covers border migration, Brandon Darby, to push back. "I'm seeing a lot of right media cover this as 'people coming illegally' or as 'illegal aliens.' That is incorrect," he wrote on Twitter. "They are coming to a port of entry and requesting refugee status. That is legal."
In an interview, Mr. Darby said it was regrettable that the relatively routine occurrence of migrant caravans — which organizers rely on as a safety-in-numbers precaution against the violence that can happen along the trek — was being politicized. "The caravan isn't something that's a unique event," he said. "And I think people are looking at it wrong. If you're upset at the situation, it's easier to be mad at the migrant than it is to be mad at the political leaders on both sides who won't change the laws."
As tends to be the case in these stories, the humanitarian aspects get glossed over as migrants are collapsed into one maligned category: hostile foreign invaders.
In November, Mr. Trump touched off an international furor when he posted a series of videos on Twitter that purported to show the effects of mass Muslim migration in Europe. Initially circulated by a fringe ultranationalist in Britain who has railed against Islam, the videos included titles like "Muslim migrant beats up Dutch boy on crutches!" "Muslim Destroys a Statue of Virgin Mary!" and "Islamist mob pushes teenage boy off roof and beats him to death!"
The assailant in one video the president shared, however, was not a "Muslim migrant." And the other two videos depicted four-year-old events with no explanation.
These items tend to metastasize irrespective of the facts, but contain powerful visual elements to which Mr. Trump is known to viscerally respond.
Last February, Mr. Trump insinuated that some kind of terror-related episode involving Muslim immigrants had taken place in Sweden. "Who would believe this? Sweden," he said at a rally in Florida, leaving Swedes and Americans baffled because nothing out of the ordinary had happened at all. "They took in large numbers. They're having problems like they never thought possible."
Like the caravan story, which apparently came to Mr. Trump's attention as he watched "Fox & Friends," the president was referring to something he had seen on cable news. And he later had to clarify that he was referring to a Fox News segment on issues Sweden was having with migrants generally, not any particular event.
The conservative National Review later called the piece in question "sensationalistic" and pointed out that a lack of government data made it virtually impossible to determine whether crime rates in the country were related to immigration.
When the president himself has not spread stories about immigration that were either misleading or turned out to be false, his White House aides have. Last year, the White House joined a pile-on by the conservative news media after it called attention to the account of a high school student in Montgomery County, Md., who said she was raped at school by two classmates, one of whom is an undocumented immigrant. The case became a national rallying cry on the right against permissive border policies and so-called sanctuary cities that treat undocumented immigrants more leniently. Fox News broadcast live outside the high school for days.
Prosecutors later dropped the charges after they said the evidence did not substantiate the girl's claims.
The story of the caravan has been similarly exaggerated. And the emotional outpouring from the right has been raw — that was the case on Fox this week when the TV host Tucker Carlson shouted "You hate America!" at an immigrants rights activist after he defended the people marching through Mexico.
The facts of the caravan are not as straightforward as Mr. Trump or many conservative pundits have portrayed them. The story initially gained widespread attention after BuzzFeed News reported last week that more than 1,000 Central American migrants, mostly from Honduras, were making their way north toward the United States border. Yet the BuzzFeed article and other coverage pointed out that many in the group were planning to stay in Mexico.
That did not stop Mr. Trump from expressing dismay on Tuesday with a situation "where you have thousands of people that decide to just walk into our country, and we don't have any laws that can protect it."
The use of disinformation in immigration debates is hardly unique to the United States. Misleading crime statistics, speculation about sinister plots to undermine national sovereignty and Russian propaganda have all played a role in stirring up anti-immigrant sentiment in places like Britain, Germany and Hungary. Some of the more fantastical theories have involved a socialist conspiracy to import left-leaning voters and a scheme by the Hungarian-born Jewish philanthropist George Soros to create a borderless Europe.
Anyone watching Fox News this week would have heard about similar forces at work inside "the caravan."
"This was an organized plan and deliberate attack on the sovereignty of the United States by a special interest group," said David Ward, whom the network identified as a former agent for Immigration and Customs Enforcement. "They rallied a bunch of foreign nationals to come north into the United States to test our resolve."