LAREDO, Texas -- The white tents that sit here on the very edge of the U.S border, with Mexico a literal stone’s throw away, represent one of the jewels in the crown of the Trump administration’s recent efforts to get a grip on the immigration crisis.

They are the temporary courtrooms set up as part of the Migrant Protection Protocols (MPP) -- known colloquially as the “Remain in Mexico” policy. That policy, established earlier this year, involves sending migrants who are trying to claim asylum back to Mexico during their proceedings -- instead of releasing them into the U.S. while their cases are heard.

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This means, officials say, that cases can be heard more quickly -- within as little as 40-60 days, as opposed to the years it sometimes takes after family units are released into the U.S. They say that’s better for the migrants, as it leaves them in limbo for less time. But they argue it also serves as a disincentive for Central American migrants who do not have legitimate asylum claims but might otherwise get into the U.S. by claiming “credible fear” of returning home.

The white tents along the border right now are meant to handle the growing asylum claims, with the backlog now at more than 800,000 cases. The courtrooms recently were set up in Laredo and Brownsville, Texas, but the administration is hoping to set up more such tents across the border soon, expanding amid greater cooperation with Mexico.

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Yet the proceedings have come under fire from immigration advocates. The group Human Rights First has called them "secretive" and described them as part of an "attack" on due process within a "sham" asylum system. The same group recently charged that they've been closed to the media and public observers. Advocates see the courts as simply another hurdle for asylum seekers.

Acting Department of Homeland Security Secretary Kevin McAleenan, center, Acting Customs and Border Protection Commissioner Mark Morgan, left, and Acting U.S. Customs and Immigration Services Director Ken Cuccinelli, right, address the media. (Adam Shaw/Fox News) 

Officials sought this week to shed light on the process. Fox News, along with other reporters, were shown the facilities in which migrants wait their turn, and also the rooms where they are put in front of a judge -- who oversees cases via video conference from San Antonio. The facility has a daily capacity of 428, but officials are hoping to expand that.

Such is the courts' importance in the multi-layered approach to tackling the crisis that four top officials went to Laredo on Tuesday to tour the facilities and defend the practices to reporters: Acting Department of Homeland Security Secretary Kevin McAleenan, Acting Customs and Border Protection Commissioner Mark Morgan, Acting U.S. Citizenship and Immigration Services Director Ken Cuccinelli and Acting Immigration and Customs Enforcement Director Matthew Albence.

“President Trump is using all the tools available to him and leveraging each federal agency to address the crisis at the southern border,” Cuccinelli said ahead of the visit. “MPP has been a highly effective tool and this visit will help explain the process to the American people.”

Migrants who are apprehended at the border and placed under MPP are sent back to Mexico, where the Mexican government gives them a social security number, a work visa, and assists with finding employment. When it is time for their hearing, they cross into the U.S. and into the tent courtrooms (officials call them "soft-sided facilities").

Migrants wait in a processing room in a Migrant Protection Protocol (MPP) center in Laredo, Texas. (Adam Shaw/Fox News)

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On site, migrants are aided by translators and also provided legal counsel. There are private hearing rooms where they can speak to lawyers and also speak one-on-one with a judge. Play areas with books and toys were also set up for children to wait in while court hearings were taking place.

“With this facility here, the whole of government approach ... bringing all the resources to bear but still giving them access to counsel, still giving them access to appropriate screening with USCIS, and doing it all here, we’re hoping we’re going to expedite that process, sift out those claims not based on merit and then those claims that are based on merit,” Morgan told reporters at the facility.

More than 42,000 migrants have been sent back to Mexico under MPP -- but it appears only a sliver of migrants ever get accepted and allowed into the U.S. When asked about this, officials didn’t say how many had been allowed into the U.S. via MPP, and the Department of Justice’s Executive Office for Immigration Review did not immediately respond to a request for that number.

Albence said that many of those put into MPP decide to give up and head home, and officials believe that as that continues to happen, it will stop migrants from making the dangerous journey north from Central America.

Critics, however, say that the administration is setting too high of a bar for entry, and have questioned the legality of the program. The program has also come under fire over a series of reports that migrants sent back to Mexico are facing violence when they get there.

A lawyer with the National Immigrant Justice Center alleged in an NPR interview that the system is meant to "foreclose" asylum.

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Morgan was asked about the reports of violence against migrants in Mexico and said that while the U.S. is assisting Mexico, what goes on inside the country is ultimately Mexico’s responsibility.

A courtroom in the MPP center in Laredo, Texas. (Adam Shaw/Fox News)

“We have to be very very careful as our own sovereign nation to paint an entire nation as a warzone,” he added. “I don’t believe that, we are not receiving that information from the government of Mexico.”

Cuccinelli said that just 6 percent of migrants claim they fear going back to Mexico, and about one in six of those are found to have a reasonable fear of going back while they wait for their hearing. Albence said as well that much of the crisis is fueled by the loopholes still present in the U.S. immigration system, and called on Congress to act.

The courtrooms are just one piece in the jigsaw of efforts by the administration to crack down on the migrant crisis -- and officials have been keen to promote what they see as initial signs of success.

The administration announced last week that immigration officials apprehended 64,006 at the border in August, a 22 percent drop from July and a 56 percent drop from the peak of the crisis in May, when more than 144,000 migrants were caught or deemed inadmissible.

Officials say that the agreements with Mexico in particular -- but also with Guatemala, El Salvador and Panama -- are helping stem the flow as those countries implement policies to staff up their borders and crack down on drug and human traffickers.

A children's play area in the MPP center in Laredo, Texas. (Adam Shaw/Fox News)

Meanwhile at home, the Trump administration has moved to end the 1997 Flores court agreement, which limits how long unaccompanied minors can be detained -- and was in 2016 interpreted by a federal court to apply to accompanied minors as well. This, officials say, has produced a powerful “pull factor” that encourages migrants to bring children with them -- even if they are not their own.

While many of its measures and rules face significant legal challenges, including the Flores rule, last week the administration saw another victory when the Supreme Court upheld a rule that bars migrants from claiming asylum in the U.S. if they have passed through another country.

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While it only gives the policy the green light while other legal challenges are ongoing, it allows the administration to bar most Central American migrants from claiming asylum in the U.S. It marked the second administration win at the high court steps in just a few months in regard to immigration. In July, the court ruled that the administration could shift money from the Pentagon to building a wall on the southern border.

In the wake of that decision, the administration is now planning to have 450-500 miles of barriers built along the border by the end of next year.