The possibility Trump’s rhetoric and policies could undermine economic, political, and societal ties has been well covered, but we don’t hear as much about the potential impact on our security cooperation. That cooperation expanded beyond a counternarcotics focus to more traditional defense activities during the Obama administration, but fighting drug trafficking remained an important part of the relationship. In jeopardizing counternarcotics collaboration, President Trump risks cutting off his nose to spite his face. I mean this is a policy priority for Trump. He’s declared the opioid epidemic a public health emergency, and… the US supply-side approach requires Mexican assistance and collaboration. In Mexico, it’s the military that has the drug-enforcement mission, which includes fighting cartels and poppy eradication. A deterioration in our defense cooperation threatens the stability and security of our hemisphere in areas from illicit trafficking to migration and natural-disaster-related humanitarian crises to destabilizing crime and violence.