TIJUANA. Mexico — Last Tuesday morning, Catardo Gómez stepped from the United States into Mexico, looked around briefly in confusion, and was immediately swarmed by microphones and cameras.

He’d made history simply by walking onto the other side of El Chaparral, a pedestrian border crossing connecting San Diego with Tijuana. Gómez was the first migrant sent back under a new Trump administration program, called the Migrant Protection Protocol, which requires asylum seekers to wait out their cases in Mexico instead of the U.S.

“I’m going straight to the place where I’m staying,” Gómez told the scrum of reporters before being hustled into a van by Mexican immigration agents. “I’m tired.”

Soon, more migrants from Central America like Gómez will be forced to make the trek back over the border as they wait for their asylum cases, which the U.S. is required by domestic and international law to hear in full before it deports asylum seekers back to their home countries. If the program is fully implemented, the implications could be massive.

Most asylum seekers who enter the U.S. through the southern border, either by presenting themselves at a port of entry or crossing illegally and surrendering to Border Patrol agents, wait in the United States while their asylum cases proceed through the severely backlogged immigration court system, which can take months or years.

But now, a growing number will be forced to wait out the process in Mexican border cities, which are often beset by the same problems of violence and poverty that the migrants fled in the first place. Some are likely to give up and return home as a result, and both supporters and critics of the program say such a deterrent effect is part of its design.

Many other migrants will either choose to settle in Mexico or seek out ways to enter the U.S. undetected, exposing them to dangerous smuggling networks. The immediate result is likely to be a growing concentration of migrants just south of the border, in cities that aren’t at all prepared for the long-term influx of the neediest populations.

“There’s no doubt that the city isn’t prepared for this,” said César Palencia Chávez, who runs a municipal office in Tijuana dedicated to caring for migrants. The office was started for Mexicans deported from the U.S. but has lately been repurposed to attend to the needs of migrants from the south. “It’s incongruent, legally, for the U.S. to have an asylum system, then for them to dare to say, ‘We’ll take your application, but we’ll make another country care for you during your case, which can take months or years’.”

The new program only aggravates an existing problem created by a policy of “metering” — or allowing only a limited number of asylum seekers through legal ports of entry on any given day — that was first instituted in the final year of the Obama administration and intensified under Trump.

Critics charge the Trump administration with instigating the kinds of chaos along the border that he claims as justification for a wall. “The Trump administration is creating yet another unnecessary crisis [and] playing a dangerous and needless game with the lives of asylum seekers,” said Beth Werlin, director of the American Immigration Council.

For many Central Americans, like Edwin Albeña, the new hurdles are not enough to keep him from trying to eventually receive asylum in the U.S. Although he’d heard of the Trump administration’s plan to force asylum seekers back into Mexico, Albeña had no intention of returning home.

“My plan is to keep waiting for them to call my number and see what they say,” said Albeña, whose family fled Guatemala after they received death threats. “You don’t leave your country unless you have a problem.”