A 10,000-strong group of migrants described by a Mexican official as "the mother of all caravans" is headed toward the U.S. 

The group was expected to arrive in Mexico City Thursday or Friday, with President Trump crediting Mexico for helping somewhat to reduce the numbers. 

He wrote on Twitter Wednesday that more must be done or "we will be forced to close that section of the Border & call up the Military."

Trump also warned Mexico over an alleged border incident in which their troops "pulled guns" on U.S. National Guard soldiers, referring to it as a possible "diversionary tactic for drug smugglers."

Responding on "Fox & Friends," the vice president of the National Border Patrol Council said the massive caravan is the result of decades of failed immigration policies. 

"Frankly, President Trump is doing everything in his power to be able to stop this crisis, but Democrats and some activists are doing everything behind his back to undermine his authority," said Border Patrol agent Hector Garza, calling on Congress to act. 

He noted that Democrats like Sen. Cory Booker (D-N.J.) and Sen. Bernie Sanders (I-Vt.) now admit there is a "crisis" along the border, as migrant families overwhelm U.S. facilities.

"The question is: what are you doing about it? The reality is that members of Congress are not acting," he argued, adding that President Trump is "putting the right pressure on Mexico" to act.

Watch the full interview above.

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