The Commanding General for Southern Command testified that the Arsenals of Central America were the major source of weapons for the Cartels.
^ This links to the State Department again.
If the United States was arming some government and the weapons "just happened" to find their way into the hands of right-wing death squads... the media would be running stories on the bloodshed (and blaming America) nightly. There would be protests calling for the U.S. to cut off foreign aid to the country, cease military coperation and cease military aid, freeze assets, etc, etc...
The State Department was arming narco terrorists in Mexico, and hundreds and hundreds of people were getting killed with weapons that were procured through the Direct Commercial Sales program, and the media hardly said a word. Sharyl Attkisson was the notable exception.
I think the architects of the whole thing counted on things being too chaotic for people to ever be able to track down which weapons were from the Mexican armories and which were from U.S. gunstores.
And with the media coverage on border issues being as bad as it was, their strategy probably would have worked, except for 2 things, Border Patrol Agent Brian Terry was killed and some BATFE blew the whistle.
The death of Brian Terry was a game changer, but the State Department's role in this has never been brought to light by the media