You might want to read up on the Opium Wars. England forced China, quite literally at gunpoint, TWICE, to buy, and continue regularly buying, England's Opium supply. China suddenly develops a massive problem with a vast increase in opium addicts, and associated problems.
Supply often does create its own demand.
However, I agree with you that the premise that this current heroin issue is not likely due to terrorists.
No Heroine is due to personal weakness and sin. It is a human failing of will over “feel good” brain deterioration and addiction. Just like marijuana. I have no sympathy for anyone hooking themselves on opiods. Unhook your self or die— Your choice and I really don’t care which decision one makes. Their business. I just dont want to pay for their choice.