Efforts by the Drug Enforcement Administration (DEA) to control the chemicals necessary to produce methamphetamine include working with foreign counterparts to cut off the supply of precursor chemicals to traffickers, and shutting down domestic rogue chemical companies which knowingly sell large quantities of the precursors to traffickers. However, traffickers and lab operators have adjusted to DEA's diplomatic and legislative initiatives, and have begun to use substitute precursors, diverting shipments from both domestic and foreign distributors. The United States has secured close cooperation in the effort to stem the diversion of ephedrine and pseudoephedrine, two major precursors, from the Swiss, Czech and Indian governments, and limited cooperation from the Mexican and Guatemalan governments. The United Nations International Narcotics Control Board plays a significant role in these efforts. References