This is the latest in a string of instances of current and former Salvadoran military personnel allegedly selling weapons to criminal groups. Last month, two officers and four soldiers were arrested over a scheme to sell  more than 1,800 hand grenades to drug traffickers and street gangs.

Earlier this month, a former Salvadoran army officer pleaded guilty to terrorism charges in a U.S. District Court, over his part in a plot to sell assault rifles to the Colombian rebel group the Revolutionary Armed Forces of Colombia (Fuerzas Armadas Revolucionarias de Colombia - FARC).

“In all of the armies of Central America, the police, the local police, all of those that have weapons, this should serve as a red flag and they must take measures to avoid being robbed,” Munguia said in a TV interview. Despite the minister's talk of robbery, none of the recent cases to which Munguia referred actually involved the theft of weapons, but rather the sale of arms by complicit current or former military officials.

El Salvador's neighbors have also been accused of failing to keep military weapons out of criminal hands. According to a diplomatic cable released by WikiLeaks, antitank weapons sold to by the U.S. to Honduras were later found in Juarez, the violence-wracked Mexican border city across from El Paso, Texas, and in San Andres island, Colombia. The cable criticized the "possible unauthorized diversion, misuse or failure to secure" weapons on the part of the Honduras government.

And as InSight noted in April, the Zetas have long been accused of arming themselves by either buying or stealing from Guatemalan military stockpiles, particularly in caches located at the Mariscal Zavala military base.

Munguia added that “the Mexican cartels have established Central America as a rearguard line for themselves, a logistical base. The cartels that operate in the south of Mexico and also those that operate in Guatemala are trying to supply themselves with arms from the Central American region.”

Munguia did not, however, outline any plans to prevent illicit sales of military arms in El Salvador. He said that the government had implemented a program of stricter monitoring of military weapons in 2009, but the past week's busts clearly demonstrate that these changes were not been sufficient to eliminate the problem.

The minister did not touch on the deeper causes of military corruption, such as low pay and a weak esprit de corps, which may be more important factors in facilitating arms sales to drug gangs.

The region was flooded with weapons during a series of civil conflicts during the Cold War. According to a July 2010 Washington Post report, more than 300,000 hand grenades were sent by the U.S. to friendly Central American countries in the 1980s, and many of those have since passed into the hands of Mexican traffickers.

The presidency of Mexico's Felipe Calderon has witnessed a steep rise in grenade attacks, with scores of them registered each year. Close to 6,000 grenades had been seized in Calderon's time in office, at  the time of the Post article.

The ready access of Central American weapons, especially combined with the increased presence of Mexican groups like the Sinaloa Cartel and the Zetas, means that much-discussed efforts to crack down on American gun traffic would likely to do little to keep dangerous weapons out of the hands of Mexico’s wealthiest groups.

Even if a robust new assault weapons ban is approved by the U.S. Congress, the institutional weakness in the region, the tighter links between Mexican groups and Central American criminals, and the glut of unused weapons available for sale all mean that alternative arms providers are close by.