The chemicals in the Manzanillo raid had been manufactured by a company in China.Precursors bound for Mexico have also been manufactured as far afield as Iraq, India and the Central African Republic, according to the International Narcotics Control Board.
The chemicals are often imported by seemingly legitimate front companies, making the search more difficult. In April, the U.S. Treasury blacklisted 12 companies in Mexico it accused of bringing in precursors to make meth.
Mexican meth production goes on speed
Phil's footnote: For years stories emerge of tons of Chinese precursors flowing to Mexican superlabs for trade extending into CONUS. Examples of DOJ/DEA collusion "for intelligence" with cartels abound.
NONe of this happens without CIA help and its been that way for along time.