the vast majority of illicit fentanyl — close to 90% — is seized at official border crossings. Immigration authorities say nearly all of that is smuggled by people who are legally authorized to cross the border, and more than half by U.S. citizens like Haley. Virtually none is seized from migrants seeking asylum.

"Our analysis, our intelligence continues to point to most of what's being smuggled at the ports of entry," said Troy Miller, the acting commissioner of Customs and Border Protection, in an interview.