First we need to designate these cartels as foreign terrorist organizations. Then we need to use special forces to take out the cartel members here with extreme prejudice. Either they leave the country, surrender, or we find and kill them here in the US. Then we go to Mexico and assist them in hunting them down in Mexico and killing them there. The cartels can not be solved with only law enforcement as they are too big and powerful and the solution will require the military.
Does not a fortified wall solve this problem for the US?
Who cares about Mexico? We just seal it off.