Trump’s letter threatened new tariffs on Mexico due to a lack of progress in challenging the country’s drug cartels.

The US stopped livestock imports from northern Mexico due to the screwworm fly threat. USDA Secretary Rollins announced border tightening and a $30M sterile fly program.

Should the flies reach the states, the larvae could infest livestock, pets, wildlife and, possibly, even people.

The United States has temporarily closed its southern border to livestock imports due to the northward spread of the New World screwworm fly in Mexico, a flesh-eating parasite posing a significant ...