Mexico has plans to deploy 6,000 National Guard troops by Tuesday to its southern border with Guatemala to slow the arrival of migrants and The Associated Press saw Mexican soldiers with black National Guard armbands stationed just north of the Guatemalan border on Saturday.

A checkpoint very close to Ciudad Cuauhtemoc in southern Chiapas state was also guarded by nearly 10 soldiers with black armbands together with federal police and immigration officers. The officials pulled at least two suspected migrants lacking required documents from vehicles.

At another checkpoint just north of Comitan in Chiapas, around 12 apparent National Guardsmen drove around backroads in the rain and dark, looking for migrants but not finding any. The AP followed them in another vehicle.

Mexico’s president has walked a fine line between enforcement and humanitarian overtures for migrants since he assumed office on Dec. 1. Originally, his administration issued thousands of transit visas for safe passage through Mexico, only to clamp down shortly after with stepped up detentions and deportations.

“The truth is that there is a great humanitarian crisis in Central America and many people out of necessity have set out to look for a life in the United States and they pass through our territory,” said López Obrador, speaking in the northern state of Chihuahua.

López Obrador said that the refusal to help foreigners in need is “anti-Christian,” adding that “we can’t turn our backs on them.”

He is lobbying for international development aid to help Central Americans remain in their countries of origin. He said on Saturday that 80 percent of the migrants crossing through Mexico, and toward the United States are from Central America.

Mexico has kindly offered refuge to migrants with credible terror as thousands remain in the country while they await court dates for asylum petitions in the United States. The understaffed and underfunded Mexican refugee commission faces a backlog of cases.

But in the past few months, police and immigration have stepped up enforcement in southern Mexico, setting up highway checkpoints, raiding a caravan of mostly Central American migrants and trying to keep people off the northbound train known as “the beast.”