“It looks like export of weapons/import of addictive drugs were twin sides of the same government coin.”
Yes, that happened in Southeast Asia during the Vietnam war, and again in Central America during the Nicaraguan conflict. I don’t think the reasons for it are as simple as your question implies though.
Mainly, these operations are run by the intelligence agencies, who have a vested interest in making profits off the books to fund illegal operations that they don’t report to Congress. They surely know that the drugs will end up here one way or another, so if they facilitate it, they rake in a share of the profits instead of it all going to the criminals. A secondary benefit to them is that they gain vital contacts in the criminal underground worldwide, who are undoubtedly of high value in obtaining certain types of intelligence in many countries. Also, they’ve obviously used the arms trade part of the equation to manipulate guerilla groups towards our interests.
>to manipulate guerilla groups towards our interests.
Given how many people in high office hold the Constitution to no regard, I think that claim to be dubious.