Heroin was basically nonexistent as a more common drug in the US until after 9/11.
I am not American, haven't been there since I was a kid, so I can only give an onlooker's perspective of course. I would agree that it's become
more mainstream, but what major US city didn't have a heroin culture, leading back to, at least, the 1970s?
Next let’s look at Columbia. They supply much of the world (along with a few other small nations) much of the cocaine. We are expected to believe they not only do that but now overnight have the ability to supply half the US with near pure heroin. Where did the infrastructure arise to do that?
They already had the infrastructure; smuggling routes, a corrupt government and a poor country acclimated to drug production and reliant on it's economy. All they needed was the poppy seeds.
I wouldn't have thought Mexico had the climate for opium production either, but nobody's denying they can supply half the US with smack.
In the book Trainspotting, written circa 1990 I believe, the 2 kilogram deal they do at the end was high grade Colombian heroin. A fictional story I know, but with cultural artifacts drawn from Irvine Welsh's real story as a Scottish heroin addict in the 1980s. If tell of quality Colombian smack made it to Edinburgh that long ago, maybe there's something more to it than the fiction written by the DEA.
What makes more sense is all those poppy fields that were decimated became operational again and either soldiers or higher up were producing very pure product to be pushed on US streets.
I do know that the US troops weren't doing anything to stop the growing of poppies, the extraction of opium or production of heroin. If they found it on someone, being smuggled at their checkpoints, it would merely be confiscated. They were "there fighting a war on terror, not drugs", according to some American politician on an Australian 60 Minutes piece about Afghani heroin I watched yesterday.
I'm not sure if you'll be able to watch that in your country, but it actually seems crazy how proper heroin was so demonized then, given what has since transpired in the opioid world (namely fentanyl).
One last thing: looking at the impurities of 4-ANPP in current US batches, I'm thinking Mexico are now producing their own fentanyl in sub-par labs, rather than importing from China. I would assume the precursors still come from China, though I could be wrong.. about everything.
Just my thoughts.