Despite these sales being illegal, the ATF required gun owners to make them under the pretense that the guns would be tracked. They intentionally weren't tracked; they were allowed to 'walk' into Mexico and right into the hands of people the ATF / DOJ knew would use them to murder innocent people.
Thousands of them went across the border, on purpose and for one purpose. That purpose was to use the subsequent murder victims - to include children - to create the political climate for gun control generally and assault weapons in particular.
Here is a direct quote from Carney's January 15th press conference, via RCP [my translated comments of what Carney likely meant are in bold brackets]:
"If these things were easy, they would have been achieved already [If Fast and Furious whistleblower John Dodson hadn't come forward, we could have blamed gun store owners for the deaths of Border Agent Brian Terry and hundreds of Mexican nationals]. If renewal of the assault weapons ban were easily accomplished, it would not need renewing because it would have happened already [Fast and Furious was very carefully planned and, as you can see, circumstances beyond our control caused it to blow up in our face. You'll also notice we had to stonewall for two years and rely on the President to assert Executive Privilege. You think an assault weapons ban is easy? Think again.]. The fact of the matter is the president is committed to pushing these proposals [The president has been committed to this issue since he was elected. Fast and Furious began in 2009. How much proof do you need?]. He is not naive about the challenges that exist [The president only pretended to be naive about Fast and Furious for the last two years but he's really not], but he believes that, as he said yesterday, if even one child's life can be saved by the actions we take here in Washington, we must take those actions. [Uh, Fast and Furious is responsible for the deaths of far more children than was the Sandy Hook but we can't exploit Fast and Furious because it was our fault]."To watch the video of Carney making the aforementioned comments, click HERE.
Here is Carney reading part of a related statement.