But the national guard, which was proposed by President Andrés Manual López Obrador and ratified by Mexico’s Congress in March, was never presented to Mexicans as a tool of border security or migration enforcement. It has not received the training of a border patrol agency and has no formal connection to the country’s migration authority. It was intended instead to fill the security void left by Mexico’s ineffective and often corrupt local law enforcement agencies as violence here continues to climb…

The law that created the force granted members the ability to inspect migrants’ paperwork and assist the country’s immigration agency.

But it remained unclear exactly what role the force would play on the border. Many worried about the militarization of southern Mexico.

“It opens a big question, because the national guard isn’t trained for this type of work,” said Gustavo Mohar, a former senior migration and intelligence official. “It’s as though you sent the FBI or police of Texas.”