Mexican President Felipe Calderon has ordered thousands of troops to be sent to Michoacan state where drug-related crime has left over 500 dead this year.
Mexican troops will enter areas under the control of drugs gangs
The government was sending more than 4,000 soldiers to areas under the control of organised criminals, the interior minister said.
The troops would conduct raids, make arrests and establish control points on major highways and secondary roads.
Michoacan state's Pacific coastline has become a haven for drug traffickers.
The authorities say that fighting between rival drug cartels has been responsible for most of the violence.
Interior minister Francisco Ramirez Acuna said they were "looking to take back the spaces that organised crime has seized".
"The battle against organised crime has just begun," he added.
Michoacan state has become a key air and sea transit point for cocaine, amphetamines and heroin bound for the US.
President Calderon, who took office on 1 December, comes from Michoacan state and has vowed to curb drug violence.
In September, gunmen burst into a bar in Uruapan city in the state, and flung five human heads onto a crowded dance floor, in an apparent warning to a rival drug gang.