Mexico is furious and demands an investigation into how belt-fed machine guns, rocket launchers, and grenades are ending up in the hands of cartel members, the country's top diplomat said. 

"The (Mexican) Defense Department has warned the United States about weapons entering Mexico that are for the exclusive use of the US army," Foreign Relations Secretary Alicia Bárcena said, who was quoted by AP News. 

Bárcena said, "It is very urgent that an investigation into this be carried out."

In June, the Mexican Army announced it had seized a dozen rocket launchers, 56 grenade launchers, and 221 fully automatic machine guns since 2018. 

The influx of military-grade US weaponry entering Mexico comes as the Biden administration fails to secure the southern border as millions of illegals flood into the US. But what's rarely discussed, in what seems like an Obama-era Operation Fast and Furious scandal, are weapons flooding Mexico from the US. 

Last week, at the SHOT Show in Las Vegas, a Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) agent from a field office in southern Texas revealed to us that the agency is very concerned about a flood of 50 cal rifles and belt-fed machine guns that are illegally entering Mexico from the US. 

The cross-border firearms trafficking of military-grade US weaponry on the southern border is very concerning. Lawmakers on Capitol Hill should investigate this worrisome development to ensure the Biden administration does not repeat the Obama-era Fast and Furious program.