Mexican authorities detained a U.S. trucker at the southwest border, after finding more than 250,000 rounds of ammunition for the assult rifles of choice of Mexico's criminal gangs.

Contralinea magazine details the routes by which guns are trafficked into Mexico, including the flow of arms from the U.S. directly to Guatemala, and then over Mexico's southern border.

U.S. President Barack Obama said his administration has no plans to implement new controls on arms sales, despite acknowledging the severity of the problem of illegal arms trafficking and the difficulty in slowing that traffic south, a Mexican news outlet reported.

Customs authorities at the border crossing from the Texas into Mexico, at Ciudad Juarez, found some 3,500 cartridges of ammunition concealed on a bus.

Guns that were sold to suspected cartel middlemen under the U.S. government's "Fast and Furious" anti-arms trafficking scheme ended up in the hands of Mexico's Sinaloa Cartel, according to a Congress report.

Congress investigators have given the FBI and DEA until July 25 to produce documents relating to a much-criticized anti-arms trafficking scheme, known as "Operation Fast and Furious."

The U.S. Justice Department has announced plans to cut arms trafficking into Mexico by monitoring the sale of assault rifles in border states, in the wake of a scandal over the "Fast and Furious" gun tracing operation.

A recently captured Zeta leader has claimed that the group obtains all of its arms from the United States, but while the announcement is sure to fuel the debate over gun control in the U.S., the group is believed to receive a significant chunk of its armory from other countries in the region.

The debate over a United States gun trafficking probe known as Operation Fast and Furious is heating up, and the Justice Department is facing questions over its knowledge of the program, which allegedly allowed thousands of guns to “walk” over the border into Mexico. But are they looking in the wrong direction?

In a sign of the increasing level of sophistication of Mexico’s drug cartels, two men admitted in court this week that they attempted to purchase military-grade weaponry -- including surface-to-air missiles -- on behalf of the Sinaloa Cartel.