U.S. drug enforcement agents have dismantled three major drug transportation rings following a 10-month investigation.

The Drug Enforcement Administration said Friday investigators broke up three Mexican and Colombian drug transport organizations and 27 U.S. distribution groups.

Officials say 164 people were arrested Thursday in the crackdown in Colombia, the Dominican Republic, and four U.S. cities - Los Angeles, New York, New Haven, Connecticut and Des Moines, Iowa.

Investigators confiscated more than five million dollars in cash, 52 firearms, along with large amounts of cocaine, methamphetamine and other drugs.

They say the distribution groups moved enough methamphetamine into the United States to have provided the drug to 22,700 users monthly.

U.S. drug czar John Walters said in an online forum that authorities are aggressively working to reduce methamphetamine production, trafficking and abuse.