Administration officials also initially said the rule would entail returning everyone who crossed the border illegally to Mexico. But the Mexican government, which was blindsided when Mr. Trump confirmed the plan this week, has since said that it would not accept all returned migrants.
“If they return people who are neither Mexican nor Central Americans, Mexico would not accept it,” said Marcelo Ebrard, Mexico’s foreign minister. Central American migrants are sent to Mexico from the United States under a different policy, one that allows them to make an asylum claim but forces them to wait in Mexico while their cases are adjudicated.
After Mr. Ebrard stated Mexico’s position in a separate briefing, Mr. Wolf said migrants from countries other than Mexico would be taken to airfields, where flights chartered by Immigration and Customs Enforcement are routinely used to deport migrants.
While the administration is already diverting asylum seekers to Guatemala, it is unclear if it is prepared to return every migrant to their home countries. Mr. Wolf said the Department of Homeland Security is currently apprehending migrants from more than 120 countries. Coordinating such transports with the government of a migrant’s home country and securing a seat on a flight would most likely require holding the migrant for at least a short period of time.
In the past, the department has been able to return migrants to Mexico by asking them if they would voluntarily go home, according to Theresa Cardinal Brown, the director of immigration and cross-border policy at the Bipartisan Policy Center. But in those cases, migrants could opt out of that process and express a need for asylum.
She said the administration’s new rule would conflict with the immigration law that allows migrants on American soil, even those who cross illegally, to start the asylum process.
“I’ve never seen this happen yet, so we have to see how this works in practice,” Ms. Brown said. “You’re faced with a conflict. A conflict of denying entry for health reasons and a right to apply for asylum.”
Zolan Kanno-Youngs reported from Washington, and Kirk Semple from Mexico City.