Calderón´s strategy contrasts with that of his predecessor, Vicente Fox, who used an elite federal police unit to target the drug trade´s kingpins.

Flows of cocaine and marijuana into the United States continued largely unabated and violence among cartels soared during Fox´s six-year term, which ended Dec. 1.

On Dec. 11, Calderón sent about 7,000 troops to his home state of Michoacán, where they destroyed about 238 hectares (588 acres) of marijuana, made more than 60 arrests and searched thousands of vehicles.

The new president has assigned another 10,000 soldiers to help the federal police fight drug gangs and other criminals.

"Calderón is clearly trying to differentiate himself from the Fox administration, which was afraid of using force," said Riordan Roett, head of Latin American studies at Johns Hopkins University´s School of Advanced International Studies in Washington. "You can´t break the back of the drug dealers, but you can deal a decisive blow that halts their expansion."

The international reach of Mexican drug gangs soared in the mid-1990s and continued to expand through Fox´s administration, according to reports by the U.S. Drug Enforcement Administration (DEA).

Mexican traffickers began developing their own routes into the United States when cartels in Colombia, the world´s biggest supplier of cocaine, began paying with drugs instead of cash to transport their production.

THOUSANDS OF ARRESTS

While Mexican authorities made thousands of arrests under Fox, the effort had little effect on curbing drug shipments, a DEA report said.

Cocaine shipments via the east coast of the United States dropped, but the amount of drugs entering across the Mexican border or nearby waters - the routes for 90 percent of cocaine smuggled into the country - remained constant over the past seven years, the report said.

Mexico is also the biggest supplier of marijuana to the United States, and Mexican cartels are increasing shipments of methamphetamine north of the border, according to the DEA.

Fox´s strategy of targeting cartel leaders spawned ferocious turf wars between gangs, says George Grayson, a professor of government at the College of William & Mary in Williamsburg, Virginia.

"The strategy had the unintended consequence of encouraging rival cartels to take over the turf of the deposed leader," Grayson said. "The kingpin strategy backfired because it encouraged intra-cartel violence, and that´s where the largest number of fatalities emerges."

Fox restricted the military to support roles after the deployment of troops backfired on his predecessor, Ernesto Zedillo. In 1997, the Army general Zedillo had put in charge of anti-drug operations, Jesús Gutiérrez Rebollo, was arrested on drug charges.

Gutiérrez Rebollo was later sentenced to 40 years in prison for drug and arms trafficking.

Some of the limitations of Fox´s policies have been on display in Nuevo Laredo, across the border from Laredo, Texas.

In June 2005, gunmen shot and killed Alejandro Domínguez, a police chief who promised a crackdown on traffickers, seven hours after he took office.

When Fox sent buses of federal police to the town to replace local officers, the Nuevo Laredo police responded by shooting at the newcomers.

Two months later, gunmen attacked a Nuevo Laredo house with automatic weapons, rockets and grenades as part of a conflict between drug gangs.

SEVERED HEADS

As drug violence in Nuevo Laredo subsided, it surged in other parts of Mexico.

Last April, the severed heads of two police officers were left outside government offices in Acapulco with a note reading, "So they learn some respect."

In September, gunmen dumped five heads on the dance floor of a bar in Uruapan, Michoacán, with a message that read: "The family does not kill for money. Everyone should know this is divine justice."

Police later arrested three Guatemalans, whom they suspected of being hit men for a Mexican cartel, in connection with the Michoacán killings.

The incident prompted U.S. Ambassador Antonio Garza to issue a travel advisory and statement saying the violence threatened business and tourism.

This year, drug-related killings have made Mexico the second-most dangerous country in the world for journalists, after Iraq, according to the Paris-based Reporters Without Borders.

Nine journalists have been killed in 2006, according to a Dec. 12 press release from the group.

RULE OF LAW

During his campaign, Calderón, 44, promised to clamp down on crime, pledging to unite the thousands of autonomous police units that operate in the country and to give life sentences to kidnappers.

"It will take time and will cost a lot of money and even human lives," Calderón said in his inaugural speech on Dec. 1. "We are going to beat crime."

The next day, Calderón promised to boost military salaries. His 2007 budget, passed by Congress on Dec. 23, included a 20 percent spending increase for defense.

Higher salaries are part of Calderón´s policy to repair the relationship between the government and the armed forces that deteriorated under Fox, said Federico Estevez, a politics professor at the Autonomous Institute of Technology of Mexico.

A sign of the improvement in the relationship was a Dec. 18 joint press conference by the country´s defense secretary, attorney general, interior secretary and head of the federal police.

The officials disclosed that they had destroyed 2,116 marijuana fields and discovered more than 1,700 more through surveillance flights.

The joint operation, along with raids in other parts of the country, have led to the arrest of more than 60 people, including Elías Valencia, the suspected leader of the Valencia cartel.

Authorities also arrested Alfonso Barajas, a leader of a cartel in Michoacán, and Jesús Raúl Beltrán, a member of the Sinaloa cartel.