Not that it's proof or anything, but supposedly ICE or a similar org has undercover backscatter XRay vans. Don't remember where I read that, but it was years ago.
> ABC News reporters Richard Esposito and Ted Gerstein provide one of the few accounts of the backscatter van in a book they wrote chronicling a year inside NYPD's bomb squad. Describing the security ahead of President Bush's motorcade to the 2004 Republican convention, they wrote that every vehicle entering the street in front of the hotel was ordered to drive between two unmarked white vans, which X-rayed each vehicle for bombs.
https://www.propublica.org/article/drive-by-scanning-officia...
> ABC News reporters Richard Esposito and Ted Gerstein provide one of the few accounts of the backscatter van in a book they wrote chronicling a year inside NYPD's bomb squad. Describing the security ahead of President Bush's motorcade to the 2004 Republican convention, they wrote that every vehicle entering the street in front of the hotel was ordered to drive between two unmarked white vans, which X-rayed each vehicle for bombs.