Illicitly manufactured fentanyl used in the US is predominantly produced in Mexico and smuggled across the very large land border between the US and Mexico.
Probably the next most common source is domestic illicit production.
Your rhetorical question suggests you thought lots of fentanyl is coming on boats on the ocean. This might be a good moment to pause and reflect on where you get your information and how you reach your conclusions.
Boats with 3-4 outboards on the back carrying large bails of some unknown "cargo" transiting well-established drug routes is obviously not a "dubious" connection. We also don't know what the intelligence was on the ground which I'm also guessing was quite substantial.
Neither you or I have the faintest clue what information was available behind the targeting decisions. Reality and your desire to frame things to justify your hatred of Trump are two completely different things.
Through small parcels from China mixed in with regular mail? People mail weed all the time and that's also illegal to go through the mail. A small parcel can carry many thousands of doses with high enough purity.
Most fentanyl in the US probably has little to no connection to Venezuela. Probably lots of other drugs, sure, but not fentanyl.
A lethal amount of fentanyl can be as small as 1-2mg. So enough fentanyl to kill 100k people would be like 50ish grams. Its not nearly some massive amount of material like you seem to think it is.
It used to come primarily from Indian and China way back in 2023... https://insightcrime.org/investigations/how-fentanyl-synthes...