Nidia Montenegro fled violence and poverty at home in Venezuela, survived a kidnapping as she traveled north into Mexico, and made it to the border city of Tijuana on Sunday for a U.S. asylum appointment that would finally reunite her with her son living in New York.

The CBP One app was set up under the Biden administration to create an orderly way for migrants to enter the U.S. and to reduce illegal border crossings.

President Claudia Sheinbaum is detaining more migrants, seizing more fentanyl and positioning her country as a key ally against China. But the U.S. stance has shifted, too.