In the 80's when the bricks came on military planes

from Killer Mike – Reagan Lyrics on Rap Genius

Meaning

A popular theory has it that the Contras (a US-supported rebel group in Nicaragua) imported cocaine into the United States in the 1980s. Delving further, it was either with the implicit permission of the US or with their direct assistance.

Gary Webb’s Dark Alliance theory never charged the military for actually transporting cocaine. Killer Mike is deliberately or not mixing this story with Frank Lucas', as seen in the movie American Gangster.

To close the circle, Jay-Z has these lines in American Gangster, a concept album spinning off the movie:
Blame Reagan for making me into a monster
Blame Oliver North and Iran-Contra
I ran contraband that they sponsored

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