The sense given by President Trump is that there’s an imminent threat at the southern U.S. border. On Wednesday morning, the tension was obvious in his tweets about a caravan of migrants making its way north from Central America.

“The Caravans are made up of some very tough fighters and people,” he wrote. “Fought back hard and viciously against Mexico at Northern Border before breaking through. Mexican soldiers hurt, were unable, or unwilling to stop Caravan. Should stop them before they reach our Border, but won’t!”

At about the same time as he was writing this, White House press secretary Sarah Sanders was on Fox News, indicating that the Mexican government had been helpful in addressing the caravan. As for the fighting, there was a clash between the migrants and police on Sunday that left one migrant dead.

Trump then made the case for his decision to send troops to the border.

“Our military is being mobilized at the Southern Border. Many more troops coming,” he wrote. “We will NOT let these Caravans, which are also made up of some very bad thugs and gang members, into the U.S. Our Border is sacred, must come in legally. TURN AROUND!”

This is the pitch in a nutshell: The caravan is dangerous and plans to enter the country illegally; therefore the military is needed immediately to turn them away.

Every part of that sentence is unfounded or false.

First of all, the caravan is not anywhere close to the border. Since organizing in Honduras and departing about two weeks ago, it has moved west into Mexico and north into the state of Oaxaca.

We noted last week that the journey by foot from the southern to northern borders of Mexico could take several weeks. That estimate may have been too low, depending on where the caravan is headed.

There’s also no indication that the caravan is “made up of some very bad thugs and gang members” to any significant degree. After Trump first tweeted about the dangerous elements in the caravan last week, the Department of Homeland Security confirmed that “there are individuals within the caravan who are gang members or have significant criminal histories.” How many such individuals are in the caravan is unclear; reporters on the ground report that it is largely families fleeing violence in their home countries.

For Trump, it’s important to emphasize criminality in the caravan because that reinforces the idea that the military is needed to repel the group at the border. Why is it important for the military to go to the border? Given that the group is still thousands of miles from the border, the answer appears to be that it offers Trump a potent visual before next week’s midterms.

On Wednesday, The Post noted that the military isn’t the only government agency that’s being conscripted to aid the Republican electoral effort. Trump has repeatedly asserted that the caravan will be a campaign issue, even lamenting last week that the mail bomber was drawing media attention away from it. Fox News and Fox Business Network continue to cover the story far more than CNN and MSNBC.

It’s important to highlight the other ways in which Trump’s military-to-the-border tweet is incorrect.

First, when a caravan approached the border last spring, it grew smaller as it progressed northward, both for the obvious reason that walking thousands of miles is not easy and because many migrants remained in Mexico instead of continuing to the United States. A few hundred made it to the border. There, they began the process to seek asylum, approaching a designated port of entry to make their claims.

In other words, the migrants didn’t simply surge across the Rio Grande, scattering to the wind, the visual that Trump seems to imply is the case. They attempted to enter the country legally.

Second, the military can’t really do much at the border anyway. The Associated Press reported that troops “will not be allowed to detain immigrants, seize drugs from smugglers or have any direct involvement in stopping a migrant caravan” thanks to laws prohibiting the military from acting as law enforcement officials on American soil. They presumably won’t cross the border into Mexico to block migrants there, either, given how Mexico might feel about several thousand troops entering its territory.

“[T]heir role will largely mirror that of the existing National Guard troops — about 2,000 in all — deployed to the border over the past six months,” the AP’s Astrid Galvan reports, “including providing helicopter support for border missions, installing concrete barriers and repairing and maintaining vehicles.”

But, again: There are no participants in the caravan who are anywhere near the border at this point anyway. Even if the military could form a phalanx along the border to forcibly repel people from entering, they’re going to have to wait for quite some time before the migrants actually arrive.

What’s going to be interesting to see is whether the troops are still in the region when the caravan, however big it ends up being, arrives at the border. Tuesday’s going to get here far before the migrants do, so the main motivation for moving the troops to the border may fade sooner than expected.