Oscar Hidalgo for The New York Times
Updated: Oct. 21, 2010
Although Mexico has been a producer and transit route for illegal drugs for generations, the country now finds itself in a pitched battle with powerful and well-financed drug cartels.
Altogether, more than 28,000 people have been killed in the nearly four years since President Felipe Calderón began his offensive against the nation’s drug organizations, with the gangs escalating fights over turf and dominance as the federal police and military try to stamp them out. Of those, over 2,000 were local, state or federal police officers, according to the Public Security Ministry. Top police commanders have been assassinated and grenades thrown, in one case into the crowd at an Independence Day celebration.
The upsurge in drug-related violence is traced to the end of 2006 when the government launched a frontal assault on the cartels by deploying tens of thousands of soldiers and federal police to take them on. Mr. Calderon has successfully pushed the United States to acknowledge its own responsibility for the violence in Mexico since it is American drug consumers who fuel demand and American guns smuggled into Mexico that are used by the drug gangs.
The violence has in some cases spilled over the border and become a source of mounting concern in states in the Southwest. And in June 2010 a Justice Department report described a "high and increasing" availability of methamphetamine mainly because of large-scale drug production in Mexico.
In August 2010, with the pace of killings rising, Mr. Calderón set up  series of high-level forums drawing Mexico's entire political establishment together, in an effort to show that the government was willing to engage its critics and listen to suggestions. In October, the government announced that it was preparing a plan to radically alter the nation’s police forces, hoping not only to instill a trust the public has never had in them but also to choke off a critical source of manpower for organized crime. It would all but do away with the nation’s 2,200 local police departments and place their duties under a “unified command.”
Desperate to highlight a success in the bloody, lingering struggle, the government staged an elaborate ceremony before incinerating 134 tons of marijuana, which officials described as the largest drug haul ever.

LOS ANGELES — Federal investigators discovered a sophisticated cross-border tunnel Thursday in an industrial part of San Diego. The half-mile tunnel was the second found this month equipped with rail tracks and carts to funnel drugs to and from Tijuana, Mexico.
Francisco Vega/Agence France-Presse — Getty Images
An entrance to the half-mile tunnel was discovered beneath the floor of a house in Tijuana. There were two exits in San Diego.
After getting a tip about drug activity at a warehouse in Otay Mesa, a thicket of warehouses and truck repair shops that hugs the Mexican border, agents with the San Diego Tunnel Task Force arrested three men there and discovered the tunnel. United States and Mexican authorities have seized more than 20 tons of marijuana since Thursday.
Mexican military investigators later detained five men in Tijuana and uncovered an entrance to the tunnel beneath the kitchen floor of a house.
Mike Unzueta, who oversees investigations for Immigration and Customs Enforcement in San Diego, said there were two entrances on the United States side, both in warehouses in the Otay Mesa area. Investigators believe the tunnel was operated by the Sinaloa cartel, one of the five largest drug cartels operating in Mexico. “This is fairly sophisticated construction,” Mr. Unzueta said. “There is a lighting system throughout, a ventilation system.”
The walls were reinforced with wood and cinder blocks, and had electrical outlets to charge jackhammers used to cut a path 60 to 90 feet underground.
On Nov. 2, federal agents found about 32 tons of marijuana and another tunnel less than a block from this one. The earlier tunnel had similar construction and connected two warehouses on either side of the border.
The authorities have found more than 75 tunnels along the border in the last four years. Most are rudimentary dirt passages, closer to the surface. Border Patrol agents discover many of the smaller tunnels when the ground beneath their vehicles caves in as they drive the dirt stretches along the border in California, Arizona and Texas, Mr. Unzueta said.
Otay Mesa, he said, has stronger ground, full of clay and decomposing granite. “You could just about build a tunnel without any reinforcement and it will stay,” he said.
The area is a target of the cartels because of its ready commercial infrastructure.
“There are literally semi trucks and warehouses everywhere you look,” Mr. Unzueta said, “and all the businesses that support that: gas stations, truck service centers. It’s an infrastructure that exists on both sides of the border.”