The thousands-strong migrant caravan attempted to force its way into Mexico from Guatemala but was mostly blocked by federal police officers and forced to sleep on a bridge that links the two countries.
The caravan of thousands of Honduran migrants marching towards the USA dramatically turned around as they reached the Mexican border in Guatemala on Friday morning, a day after hundreds of their comrades faced off with police.
"So are you going to go back to that?"
"Everyone I talked to said they had no other choice", Weir said. If that doesn't work out, we're calling up the military-not the [National] Guard.
On Thursday, Mr Trump thanked Mexico in a tweet for the decision to send hundreds of police officers to meet the migrant caravan at the border.
The migrants include many parents travelling with young children.
Marta Sánchez, founder of the Mesoamerican Migrant Movement, which organises an annual caravan of mothers searching for their children who disappeared while trying to reach the U.S., said: "This is not a caravan, it's an exodus".
Mexican President Enrique Pena Nieto described the situation as "unprecedented".
They have also started giving some people 45-day visitor's permits, which in theory could allow them time to reach the USA border. Even if it's within his authority as president, he would nearly certainly face stiff resistance, obstruction, and nigh unending court battles over it - much the same response he might expect, say, for deploying the military to enforce a closed border.
Since the mid-1970s, migrants from Central and Southern America have exploited Mexico's relatively lax policies on border security to enter the US illegally.
Last night a group of migrants tore down the border gate and were seen rushing towards Mexico. "That would really hurt legal transit between the two countries and manufacturing and trade, which would affect American workers", Selee said. They might as well turn back.
"Because many of those people, a percentage, a fairly big percentage of those people are criminals and they want to come into our country and they're criminals".
Mexican authorities haven't said whether anyone from the caravan will be permitted to travel to the U.S. border.
On Thursday, Mexico's ambassador to Guatemala, Luis Manuel Lopez Moreno, met with migrants camped out on the border to try to discourage them from crossing illegally.
Mexican officials said those with passports and valid visas - only a tiny minority of those trying to cross - would be let in immediately.
Hundreds of people, who are waiting for court dates, are being released as border officials say they don't have the capacity to hold all of the migrant families.
Mexico has sought help from the United Nations' refugee agency, which may have the effect of dispersing the caravan.
They've travelled across a continent but thousands of Central American migrants are now trapped on Mexico's southern border after trying to break through a frontier fence.
The Republican billionaire has made curbing undocumented immigration a keystone of his presidency.
Donald Trump fueled his 2016 campaign with fiery immigration rhetoric, visions of hordes flowing across the border to assault Americans and steal their jobs.
It's unclear how serious Trump is about sealing the border or if this is more of a political move to drum up his base before the midterm elections in less than three weeks.