Law enforcement agents called them ultralights. Picture a canvas chair and a small engine tied to a hang glider. They flew over from Mexico with a basket of drugs the pilot dropped on U.S. soil before returning home.

That was in 2008. Transnational criminal organizations now use drones to drop fentanyl, meth and cocaine in border communities like El Paso and to guide migrants jumping over the border wall. They’re also attaching grenades and homemade bombs to them to harry rivals in southern Mexico and attack soldiers in Chihuahua.

“The use of drones on the border is not new,” said Victor Manjarrez, Jr., a former U.S. Border Patrol chief in West Texas and Arizona. “The cartels are very measured of what they do in the U.S. for fear of our response. […] But there always could be a nutcase there, a lone wolf who says, ‘I want to make my mark in life.’ That is what I fear.”

That means the cartel threat to the U.S. is real.