From a very good piece at VICE by Keegan Hamilton, who closely followed the New York trial of former Mexico public security chief Genaro García Luna:

For watchdogs like Adam Isaacson [sic.], director of defense oversight at the Washington Office on Latin America, it’s no surprise that the U.S. government turned a blind eye toward García Luna while he was in power.

“It seems pretty clear that the DEA and other parts of the United States government knew that Garcia Luna was not somebody that they could fully trust, and that, in fact, he may have been colluding with armed groups or with organized crime,” Isaacson told VICE News. “But they still found him useful because he was going after other organized crime groups at the same time.”

Isaacson pointed to examples beyond Mexico, such as Honduras and Brazil, where the U.S. has provided funding and training to state security forces linked to corruption and human rights abuses, and said it’s no longer shocking—it’s simply business as usual in the war on drugs.

“Their mission is not to make corruption go away,” Isaacson said. “Their mission is to break a drug organization and get as many tons of drugs seized as possible so it doesn’t make it to the United States. And if that means making common cause with bad guys to go after other bad guys, they’re going to do it without regard to the institutional or accountability damage that that might do in the countries that they’re working.”