The Mexican government is allowing domestic marijuana and opium poppy production to climb to record levels, as soldiers who once cut and burned illegal crops here in the vast Sierra Madre mountains are being redeployed to cities to wage urban warfare against criminal gangs.

Since President Felipe Calderon ordered his troops into the streets in late 2006, the acreage dedicated to marijuana farming has nearly doubled in Mexico, according to technical reports by the U.S. government and the United Nations, data provided by the Mexican military, and interviews with law enforcement agents and growers.

The acreage devoted to opium poppies has also soared, according to the U.S. State Department, making Mexico the second-leading heroin producer in the world, after Afghanistan, whose crop goes mostly to Europe and Asia.

Five years into the fight against Mexico’s drug cartels, the country’s sagging eradication efforts expose a major weakness in a U.S.-backed strategy whose leading goal for American officials has been a reduction in the amount of drugs on U.S. streets. With Mexican security forces busy fighting mafia gunmen in places such as Monterrey and Acapulco, their capacity — or commitment — to rip up rural marijuana and poppy plants has fallen off, sending a surge of fresh dope over the U.S. border.

U.S. officials say they are worried about increased drug production in Mexico but have limited ability to push for a more aggressive eradication campaign, given the Mexican government’s urgent need to do something about violence and insecurity in the cities. And by trying to seize high-value shipments of South American cocaine from the cartels and capture or kill top mafia leaders, both governments hope they can do more damage to the cartels’ networks and finances.

Mexican troops hacked and burned 77,500 acres of marijuana in 2005, the year before Calderon took office. But last year they cleared just 43,000 acres, according to the Mexican army and marines. Marijuana seizures at the United States’ southwest border went from 1 million kilograms in 2006 to 1.5 million kilograms last year.

As the acreage of poppies destroyed has dropped, Mexican heroin production has boomed, from 8 metric tons in 2005 to 50 metric tons in 2009, according to the U.S. government. Heroin seizures along the U.S.-Mexico border have tripled during the same period.

In Mexico’s prime dope-growing region, known as the Golden Triangle, local farmers say the best cash crops are still the illegal ones.

“Look at these mountains. What else are we going to do?” said grizzled, 79-year-old Sabino Juarez, waving his machete toward the steep green folds of the Sierra Madre in northwest Mexico’s Sinaloa state.

Juarez said most of the poor families in his nearby rancho grow marijuana, and the military has left them alone in recent years. Drought was the bigger worry this season. “It was bad for corn, bad for beans and bad for mota,” he said, using the slang in Mexico for marijuana.

Come late October, the clandestine fields of sticky marijuana are head high and ready for harvest in Mexico’s rugged mountains, and the pretty red, white and purple poppy buds are fat with opium sap in the remote valleys.

‘A change in strategy’

The Calderon administration has steadily, and quietly, moved away from Mexico’s decades-long zeal for eradicating drug crops in the field, a practice that was once at the heart of Mexican and U.S. anti-drug strategy.

“Yes, it is a change in strategy, as the army now gives priority to catching criminals and seizing cocaine, which is far more valuable to the cartels” than marijuana or heroin, said Raul Benitez, an expert in drug trafficking and national security at the National Autonomous University of Mexico.

The Mexican government, Benitez said, also cares less about marijuana cultivation these days because the U.S. government appears to care less.

“Because in the United States there is a lot of marijuana growing and being sold, and it is not really prosecuted. In fact, in some states, it looks almost legal,” Benitez said, referring not only to the wide availability of pot in the United States but also the explosion in shops that sell medical marijuana, now legal in 16 states and the District of Columbia.

The reduction in drug crop eradication also dovetails with Calderon’s growing frustration with the U.S. government and American drug consumers. “We are living in the same building, and our neighbor is the largest consumer of drugs in the world, and everyone wants to sell him drugs through our door and our window,” the Mexican president said this month in New York City.

Calderon complains bitterly that the United States has done little to control the flow of weapons and cash into Mexico, and that demand for drugs north of the border appears insatiable.

Mexican public-sector spending on security has increased sharply during the Calderon administration, from $1.7 billion to more than $12 billion, according to calculations by Mexico Evalua, a think tank.

Supply meets demand

The sharp turn away from drug crop eradication by Mexico, which once had the most aggressive program in the world, is frustrating to U.S. law enforcement agents and diplomats, but they are careful not to directly criticize their close ally.

“There has been a reduction in eradication,” said Rodney Benson, director of intelligence for the Drug Enforcement Administration, who noted that the Mexican military forces were spread thin. “I can only give the government the highest praise for its remarkable success in targeting cartel leadership. But you need to do both” — go after leaders and reduce supply. But, he added, “there are only so many forces to go around.”

In contrast, U.S. officials heap praise on eradication efforts in Colombia, where 360,000 acres of coca were destroyed last year by hand or aerial spraying. Coca eradication is also credited with helping drive up average street prices for cocaine over the past four years, from $101.10 to $189.24 per gram, according to DEA figures.

But heroin from Colombia is being supplanted by the Mexican “brown” and “black tar” varieties. The Justice Department’s National Drug Intelligence Center, in its latest threat assessment, concluded that “the availability of heroin in the United States — and the number of markets in which it is available — is increasing as a result of increased production in Mexico, even as Colombian production declines.”

Still, many drug policy analysts will not mourn Mexico’s move away from eradicating pot and poppy in the fields. “Eradication is not a very effective strategy. I would end the programs, I would end the whole exercise. Because it really has no effect on availability in the United States,” said Alejandro Hope, a security consultant for Mexico Evalua, who said the trafficking organizations simply adjust how much they plant against how much they expect to be destroyed.

“So the supply always meets the demand,” Hope said. “No matter what.”

In the tiny mountain town of Santiago de los Caballeros here in Sinaloa, Mexican federal workers arrived with armed escorts to hand out cash to locals, part of a program to encourage them not to grow marijuana and opium poppies. Police officers with body armor and automatic weapons stood guard as elderly women and young mothers clustered under a tent where folding tables were stacked with calculators and colorful peso notes.

The neediest families could get about $150 a month, the women said.

But a single kilo of dried marijuana in the area could fetch $100.

“People around here just grow a little bit, to survive,” said Herminia Paya, who was selling plastic headbands, bracelets and other curios to the women in line.

Down the road, in the town square of Badiraguato, the county seat of the municipality where many of Mexico’s most notorious narcos hail from, farmers said the military was still destroying marijuana crops, just not as much as in the past. With harvest time getting underway, there were no military checkpoints on the highway or helicopters overhead.

“We grow everything here in Badiraguato,” said Juan Martinez, 60, sitting under a tree next to the cathedral. He spat on the ground. “And anybody who doesn’t like it can take a hike.”

Researcher Gabriela Martinez contributed to this report.