An agency of the U.S. government is being accused of putting weapons in the hands of Mexican drug cartels that killed a U.S. border agent and hundreds of Mexicans.
The Bureau of Alcohol, Tobacco and Firearms allowed several thousand guns - including assault rifles -- to be sold in the U.S. to violent drug gangs.
William McMahon, the head of ATF's Western region, testified that the agency had good intentions when it launched Operation Fast and Furious in 2009.
The goal of the operation was to lead ATF agents to high-profile traffickers. But McMahon said that looking back, there are things ATF would have done differently.
Appearing before the House Oversight and Government Reform Committee, he said he was committed to dismantling criminal networks on both sides of the border, but that "in our zeal to do so, and in the heat of battle, mistakes were made. And for that I apologize."
ATF Special Agent John Dodson, another witness, also admitted the operation could have been executed better.
"This is not a matter of some weapons that had gotten away from us or allowing a few to walk so that we could follow them to a much larger significant target. Allowing loads of weapons that we knew to be destined for criminals was the plan. This was the mandate," Dodson testified.
"I remember a lecture by Army Lieutenant Dave Grossman and I borrow from it now. ATF is supposed to be the guardians -- the sheep dogs that protect against the wolves that prey upon us -- especially along our southern border. But rather than meet the wolf head on, we sharpened his teeth, added number to his claw, all the while we sat idly by watching, tracking, and noting as he became a more efficient and effective predator," he added.
The committee wants to find out who in the Justice Department knew about this plan and why the Mexican government was not notified.
The ATF won't say how many agents are working on Fast and Furious for fear that disclosure would compromise the security of the operation. Overall 260 ATF agents are assigned to the entire U.S.-Mexican border area and participate in various Project Gunrunner probes.