The U.S. border with Mexico is known as much for the smuggling of drugs into the United States as it is for the smuggling of illegal immigrants. It is less well known for the massive smuggling of guns from southwestern American guns stores to Mexico, particularly the lethal military-style assault rifles that have helped fuel the drug cartel wars that are responsible for killing more than 40,000 in Mexico since 2006.

Since the 2004 repeal of the U.S. assault-weapons ban, the federal enforcers of America's meager gun laws, the agents of the Bureau of Alcohol, Tobacco and Firearms, have been swimming upstream trying to root out the straw purchasers of assault rifles and other weapons and ammunition that form the flood of weaponry from the U.S. into Mexico. Figures compiled by Mexico, according to a report by The New York Times, reveal that tens of thousands of weapons seized from drug cartels in the past four years - and three out of five assault weapons - came mainly from the United States.

It is that history, coupled with the absence of U.S. laws that could help identify or restrict the availability of weapons to straw purchasers in America, that apparently spawned the "Fast and Furious" operation to monitor gun-running. That operation has now become the controversial target of a House investigation.

The operation apparently was flawed, in that it monitored some gun traffickers, rather than arresting them, in an attempt to trace the route of weapons from underling gun-runners to the major purchasers of the weapons in Mexico. The apparent goal may have stemmed from a 2010 audit by the Justice Department which criticized the ATF for arresting too many small buyers in the U.S. instead of tracking down the major purchasers for criminal organizations and drug cartels.

In any case, Fast and Furious apparently went bad in one tragic way: two of the guns being tracked were confiscated in connection with the shooting death of a U.S. Border Patrol agent, Brian A. Terry, in Arizona in 2010. His death, and information from ATF whistle-blowers about the nature of Fast and Furious, have generated intense criticism against the ATF for allowing monitoring of guns being transferred across the border instead of stopping and arresting the gun-runners.

House Republicans have good reason to investigate what went wrong and what should be done to improve the ATF's enforcement strategies. But it is clearly obvious that the Republicans in control of the hearing want to attack and weaken, rather than strengthen, the ATF and its operational capacity. Rep. Darrell Issa, R-Calif., sharply cut off testimony about gun-control legislation.

Advocates of reasonable gun control, including members of the ATF, have contended for years that better records of gun sales and timely access to those records would help them monitor and interdict straw purchases and major gun-running operations. Indeed, a number of record-keeping improvements - including mandatory background checks on all weapons purchases at the nation's currently wide-open gunshows - along with monthly limits on legal purchases would allow ATF officials to begin to get a grip on gun-running, from state to state and across borders.

Republicans, and the National Rifle Association, which leads the GOP's anti-gun-law positions, have refused to consider or accept reasonable restrictions on largely unregulated weapons sales and advanced technology to trace ballistic patterns and ammunition. As long as their anti-control agenda holds sway, the ATF will have to function with its hands tied behind its back.

The hearings should not excuse the ATF for a flawed operation. But they also should not pre-empt the possibility of laws on gun sales that would mitigate the appalling violence in Mexico and on the streets of America that results from the absence of sane gun control.