Mexico deployed nearly 15,000 soldiers and National Guardsmen to its border with the US, the army chief said Monday — admitting they are detaining migrants who try to cross after the policy triggered a backlash, a new report said Monday.

Under pressure from President Trump to slow the surge of Central American asylum seekers crossing the border, Mexico promised earlier this month to reinforce its southern border with 6,000 National Guardsmen, but had not previously disclosed the extent of the crackdown on its northern border, Agence France-Presse reported.

“We have a total deployment, between the National Guard and army units, of 14,000, almost 15,000 men in the north of the country,” Defense Minister Luis Cresencio Sandoval said at a press conference alongside President Andres Manuel Lopez Obrador.

Asked whether those forces were detaining migrants to prevent them from crossing, Sandoval replied: “Yes.”

“Given that [undocumented] migration is not a crime but rather an administrative violation, we simply detain them and turn them over to the authorities” at the National Migration Institute, he said.

The government has faced criticism for stopping migrants from crossing the US-Mexican border.

National Guardsmen and police have been patrolling the border in groups, detaining migrants who attempt to cross.