Nuevo Laredo, Mexico — The Trump administration's immigration crackdown on the southern border is expanding: all asylum seekers are now required to "Remain in Mexico" to await their day in U.S. immigration court. That wait is long and dangerous.

The streets of Nuevo Laredo are often called "los caminos de carteles." Highly coveted smuggling routes are now a dumping ground for migrants.

Kensy Medina and Marvin Torres arrived at one of the shelters there two days ago. As a part of the "migrant protection protocol" or MPP. It's a program that sends asylum seekers back into Mexico to wait for their day in court.

"In this area right here this is safety for them, but if you just walk out that door it is not safe, that the cartels come by to pick them up to kidnap them," Torres told CBS News, which was translated from Spanish.

They showed the documents agents gave them before leaving the U.S.

Marvin Torres CBS News

Through translation, the documents say the migrants should arrive at the port of entry listed on September 17, 2020, to ensure they have time to be processed and meet with an attorney. That's a year from now.

MPP has expanded to include all those who seek asylum at the southern border. Some 51,000 asylum seekers have been sent to Mexico under this policy, according to White House data.

"With MPP, migrants are receiving due process and protection while the United States is restoring integrity to our immigration system," said Acting Commissioner of the U.S. Customs and Border Protection Mark Morgan. "We're closing the loopholes."

Dr. Fabiola Pintero, with Doctors Without Borders, said the moment migrants leave the federal immigration building, they are being watched. A new commodity for the cartels.

"We have talked in the shelters about this situation are MPPs, most of them, more than half of them have suffered some kind of violence here," Pintero said.

At another shelter, director Olivia Campos said six people were kidnapped outside its walls a few weeks ago.

"It's very dangerous here," Campos told CBS News.

In these shelters, fear is only out-matched by the uncertainty most families now face.

"There's no way he can stay here, there's no way to stay here, " Torres said through translation. "There's no paper, they don't have paperwork they don't have anything to help them stay here."

The mayor of Nuevo Laredo told CBS News they have local officers working with the federal agents to keep migrants safe. But that's not what's been seen or heard since CBS News has been here.