The figures from a Mexican army raid on a stash house used by a drug cartel in Reynosa are staggering. Express-News investigative reporter Todd Bensman recently revealed that the November operation uncovered 540 rifles, 500,000 rounds of ammunition and 165 hand grenades, along with other military ordnance.

Gangs don't have armories like that. Militias do. And this one — one of countless others in Mexico — was sitting right across the Rio Grande from McAllen.

Here's another shocking figure. The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives was able to trace the serial numbers from 383 of the rifles seized in Reynosa. Eighty percent of them were purchased from licensed firearms dealers in Texas.

Mexican instability is an American problem. Violence south of the border can easily spread to violence on this side of the border.

Moreover, the American appetite for illicit drugs is fueling the narco wars in Mexico. And guns purchased in Texas and illegally transported across the border are arming the cartels.

State Sen. Tommy Williams, R-The Woodlands, has introduced a measure that would raise the penalty for unlawfully carrying a weapon or transporting prohibited weapons across the border, unauthorized use of another person's motor vehicle while crossing the border and harboring a fugitive with the intent to cross the border.

All these offenses would be upgraded to second-degree felonies.

Given the gravity of the situation in Mexico, those are appropriate changes to Texas law. But the more important issue doesn't have to do with state law or even federal law. It has to do with the manpower to enforce those laws.

Firearm tracing through the ATF's Project Gunrunner provides valuable information about the flow of weapons into Mexico. Unfortunately, southbound inspections by the Customs and Border Patrol to stop that flow is inappropriately funded as only a minor facet of border security.

That needs to change. Congress and the Obama administration need to put more emphasis on uncovering weapons transfers before they reach Mexico, and the adminsitration is vowing to do so.

That's a necessary commitment. Tougher laws are only as effective as their enforcement. In the case of gunrunning, an ounce of prevention on the U.S. side could stop tons of weaponry from reaching the drug cartels — and creating havoc on both sides of the border.