Via Reuters, interesting details on the fentanyl manufacturing supply chain:
...Javier said the Chinese supplier sends some precursors by air in small packages to Mexico City’s international airport. Many are piperidines, compounds at the core of fentanyl’s structure. A little goes a long way. Javier declined to go into details about where the packages go immediately after clearing customs. He did say they’re often flown out of the capital on small planes to Sinaloa.
Chemicals needed in greater volumes, such as propionyl chloride, often come via cargo ship. Javier said his group moves “tons” of precursors through the Port of Manzanillo each year. In addition, he says his team pays millions of dollars in bribes annually to officials at the port — including to customs agents and, more recently, naval officers — to ensure the goods exit the port smoothly.
“We spring the chemicals out without problems,” Javier said.
Interdiction efforts when significant bribery is in play is probably pretty tough.