They were openly encouraging the Mexican Government to sue US gun manufacturers in US courts. They were hoping for a multi-billion dollar lawsuit to drive the issue.
That all fell apart when, with the death of Terry, the gun-running by the US government itself became public.
There was another side issue. The US government had struck a deal with one cartel to inform on the other cartels, and was actively protecting that cartel. It looks to me that the weapons being sold over the border were going to that cartel.
Thanks, that makes perfect sense!