caravan. He also appeared to threaten a revamped trade deal with Mexico and Canada.
Trump's frustration appears to stem in part from record levels of immigrant parents entering the U.S. with children in the three months since his administration ended family separations at the border.
Dozens of Arizona National Guard members were among those deployed to the border.
Mindful that many members of the caravan are fleeing poverty and violence, United Nations officials at the shelters will decide which migrants have legitimate claims for refugee status.
But Marcelo Ebrard, who has been picked as Mexico's next foreign minister, downplayed the comments and said Trump was appealing to his domestic political base.
The Mexican ambassador to the US made the claim that they had reason to believe the migrant caravan from Honduras heading to the USA border was politically motivated.
Trump claimed that "Criminal elements and DRUGS [are] pouring in" and that it is "All Democrats [sic] fault for weak laws!"
"It's a challenge that Mexico is facing, and that's how I expressed it to Secretary Pompeo", Videgaray told a news conference alongside his US counterpart.
At a news conference with Videgaray, Pompeo called illegal migration a "crisis" and emphasized "the importance of stopping this flow before it reaches the USA border", while also acknowledging Mexico's right to handle the crisis in a sovereign fashion. Migrants broke down the gates at the border crossing and began streaming toward a bridge into Mexico.
Several thousand Honduran migrants moved this week through Guatemala, and some were trying to cross to Mexico on Thursday, according to local media.
The migrants are fleeing Honduras where they say they have no prospects.
"We are still in a position to support our federal partners if asked", he said.
"We're going to wait for those still on their way but who are close by" before trying to cross, Mario Mejia, who seemed to be one of the migrants' leaders, told AFP.
"Guatemala, El Salvador, Honduras... we need to make sure that the root causes are solved".
Migrants who want to apply for refuge in Mexico were welcome to do so, they said, but any who decide to cross illegally and are caught will be detained and deported.
The migrants say they organized for the long and hard journey on social media, but Washington suspects the group has been organized as a deliberate provocation.
Mexico had also dispatched additional police to its southern border after the Casa del Migrante shelter on the Guatemalan side of the border reported that hundreds of Hondurans had already arrived there.