U.S. has sent 240 migrants back to Mexico under experimental policy, which has expanded along California border

A policy of sending Central American asylum-seekers back to Mexico while their claims are processed has recently expanded to a port of entry near Calexico in California. (Scott Olson/Getty Images)

Homeland Security officials said Tuesday they have sent 240 migrants back to Mexico since January under an experimental new policy that requires Central American asylum seekers to wait outside U.S. territory while their asylum claims are processed.

The policy, known as “Migrant Protection Protocols,” has been expanded in recent days to the Calexico port of entry in California, said Department of Homeland Security officials who spoke on the condition of anonymity to describe the implementation of the measures.

A small number of migrants who were arrested for crossing illegally between U.S. ports of entry in the San Diego area also have been returned to Mexico under MPP, DHS officials said.

The measures rely on a provision in U.S. immigration law that allows authorities to send back migrants who arrive through a third country to that foreign territory. Immigrant legal advocates are seeking an injunction in federal court to block MPP, which the Trump administration says is necessary to contend with a recent surge of border crossings.

More than 76,000 authorized migrants were taken into custody last month, led by a record number of migrant families. DHS officials say they are implementing the MPP program slowly and cautiously to make sure they do not overwhelm the Mexican border cities that receive them.

“The numbers so far have been very low,” one DHS official told reporters. “We anticipate that as we grow and expand the program along the southern border, they will grow exponentially.”

Mexican officials are cooperating with U.S. authorities, receiving the migrants and providing them with temporary visas. But they say the Trump administration has imposed the measures unilaterally.

DHS officials have said they plan to implement MPP in the El Paso area next, without providing a timeline.

Migrants who are subject to MPP receive an initial screening and a court appointment, and they are instructed to return to the border for transportation to the courthouse.

The measures are designed to break the pattern — derided by the Trump administration as “catch and release” — which generally allows asylum seekers to live and work in the U.S. interior while their immigration cases are pending, a process that can take years.

Underage migrants, Mexican nationals and other categories of migrants are not included in the MPP actions, and to date, those who express a fear of harm if returned to Mexico also have been excluded, DHS officials said.