Former President Donald Trump responded to questions on fentanyl overdoses by hammering President Joe Biden on illegal immigration. But in the 2023 fiscal year that ended Sept. 30, 86% of fentanyl trafficking crimes were committed by U.S. citizens, according to the U.S. Sentencing Commission.

At a hearing in July 2023, James Mandryck, a Customs and Border Protection deputy assistant commissioner, said 73% of fentanyl seizures at the border since the previous October were smuggling attempts carried out by U.S. citizens, with the rest being done by Mexican citizens.

Fentanyl seizures at U.S. borders are largely at official points of entry, including land crossings and airports. Both Trump and Biden have supported detection equipment at the border.