From page 15 of U.S.-Mexican Security Cooperation: The Mérida Initiative and Beyond
The State Department has provided $15 million in equipment and training assistance, including NII equipment, mobile kiosks, canine teams, and training for INAMI officials in the southern border region. It plans to spend at least $75 million in that area. The Department of Defense has provided training and equipment to Mexican military forces as well.
Additional information is provided in INCREASED ENFORCEMENT AT MEXICO’S
SOUTHERN BORDER
An Update on Security, Migration, and U.S. Assistance
(this is a 40 page report, so I can't quote everything)
Walls and barriers: In fall 2014, Ferrosur constructed a concrete wall topped with barbed
wire that extends roughly one kilometer (approximately 0.6 miles) along the train tracks
in Tierra Blanca, Veracruz. In addition to impeding migrants from accessing the train, the
wall complicates migrants’ access to the Decanal Guadalupano migrant shelter, which has
provided shelter and assistance to migrants since 2003. [65] Before the PFS was announced,
Ferrosur had begun efforts to impede migrants from boarding the train. In 2013, the train
company built a wall, similar to the wall in Tierra Blanca, to impede migrants’ access to
the train in Coatzacoalcos, Veracruz.[reference 66] In 2012, Ferrosur lined both sides of the tracks in
Apizaco, Tlaxcala with concrete posts, which has made it nearly impossible to board and
disembark the train, and has resulted in numerous injuries