Mexico has deployed thousands of security personnel around the country as part of a new National Guard.
They're supposed to tighten Mexico's borders and fight crime in the most violent areas of the country.
The force is controversial because of its militarised nature. Mexico's government promised the United Nations will train the personnel on how to respect the human rights of the civilian population. .
But that hasn't happened yet.
Al Jazeera's John Holman reports from Tapachula, Mexico.