Combating Mexican cartels that traffic in fentanyl is the top priority of the U.S. Drug Enforcement Administration (DEA), the agency’s chief said in a video message last week. “Every day I walk into DEA headquarters, I’m reminded of DEA’s mission. I see the faces of fentanyl. I see Americans that have lost their lives at the hands of the cartels. DEA is poised to lead this fight against the cartel...