Now add to that another risk: fueling the “narco wars” in Mexico that have pitted government troops against powerful drug traffickers. At least 22,700 have died in drug-war-related violence in Mexico since 2007, by some estimates. That’s more than eight times the number of Americans killed on September 11, 2001.

“America’s love affair with illegal drugs fuels the major Mexican drug cartels,” former head of the Drug Enforcement Administration Robert C. Bonner said. “[It] allows them to be powerful, corrupt, and to engage in a lot of violence and intimidation in Mexico and elsewhere.” Bonner has also served as a federal judge and Commissioner of U.S. Customs and Border Protection.

Marijuana is often viewed as the most innocuous of illicit substances, and it is the most commonly used illegal drug in the United States. But it is hardly innocent. Many Americans think of cocaine and heroine when they think of the drug wars in Mexico, but by some estimates, marijuana is the most significant source of revenue for the cartels.

“Marijuana represents a good portion of the cash flow of the Mexican cartels, and it represents the most key drug on the southwest border by huge amounts,” Drug Enforcement Administration spokesman Rusty Payne said. “I don’t think people realize that when they increased the demand for marijuana in the United States, oftentimes they directly benefit drug trafficking and the violent cartels in Mexico.”

Harvard economist Jeffrey Miron says that “prohibition pushes the market underground … [resulting in] ancillary negatives,” like the violence and corruption along the border.

Miron points out that not all marijuana in the U.S. is trafficked from Mexico; some is raised domestically. But because of a lack of any product regulation, it is often impossible to know from where – and from whom – a given amount of marijuana comes. Many users inevitably, if unwittingly, help fund the drug wars that haunt the United States’ southern neighbor.

In a July 2010 prepared congressional testimony for a House hearing on international counternarcotics strategy, Adam Isacson, senior policy analyst at the Washington Office on Latin America reported: “Decreased violence in Colombia has been offset by a sharp rise in drug-related homicides in Mexico. Today, Mexico is the center of gravity for groups involved in illegal drug transshipment, which is by far the most profitable link in the drug trafficking chain.”

The tactics and levels of organization of the Mexican cartels also have changed. The Council on Foreign Relations reports that “Violence reached acute levels [in Mexico] in 2006 and has only worsened since then; decapitations became common and cartels began disseminating videos documenting gruesome deaths – ‘narco messages’ – to threaten rival cartels and government officials. While initially the majority of violence was between cartel members, in the past two years, police officers, journalists, and politicians have become frequent targets of drug killings. In May 2008, for instance, Mexico’s acting federal police chief was killed in a drug hit.”

The reports of death and conflict continue. A pregnant American consulate worker and her husband were killed in broad daylight in March of this year, in the violence-ridden border town of Ciudad Juarez. And on July 22, Mexican officials received a tip that led them to several mass graves in the northern part of the country. At least 50 bodies were buried there.

Drug-related conflict could also be creeping over into the United States. The Maricopa County attorney’s office in Phoenix told the New York Times that it received 241 reports of border-related kidnappings or hostage-takings in 2008, compared with just 48 in 2004.

Those numbers pale in comparison to the enormous toll the drug wars have taken south of the Arizona border.

“The Mexican drug cartels pose a national security threat to Mexico in the same way that, at one time, the Colombian drug cartels threatened the Colombian state,” Bonner said.

That, in turn, poses a problem for Mexico’s northern neighbor.

While Bonner said he does not think drug cartel activities pose a substantial national security threat to the U.S. itself, the Mexican government’s battle with the cartels is still of significant concern to the United States.

“It would be untenable [for the U.S.] to have a state on our border that is controlled by narcotraffickers,” he said.

On this side of the border, in 2008, over 40% of American 12th graders had used marijuana at least once, according to the National Institute on Drug Abuse.

Bonner said that while he believes cocaine and methamphetamines are ultimately more profitable for the cartels, “it all adds up.”

When young Americans buy even small amounts of marijuana that is trafficked by the cartels, “they’re contributing to criminal organizations that have engaged in and are engaging in wanton violence in Mexico and elsewhere,” Bonner said.

“They’re aiding and abetting.”

This recent video shows just how far that policy has set in, with U.S. soldiers not only permitting poppy farming but essentially helping Afghan farmers grow the crop.

Although some soldiers and Afghans see progress in various areas, many criticize the tacit support of poppy growing, according to a report on the counter-narcotics effort from the inspector general for the State Department.

The concern is that poppies used for the opium trade wind up supporting terrorism. They provide much of the funding for the Taliban, according to estimates by the United Nations Office on Drugs and Crime.

The U.S. policy now hopes to prevent that by focusing only on drug traffickers, so as not to affect farmers for whom poppies are their sole livelihood.

Tom Schweich, the U.S. ambassador for counter-narcotics and justice reform in Afghanistan from 2007-08, debates the effectiveness of any policy that fosters poppy growing and does not include at least some amount of eradication.

“That’s like getting rid of a tree by cutting the branches instead of the roots,” Schweich said. The policy adopted by Holbrooke is more politically based than attending to actual situation, according to Schweich, who helped shape policy that included eradication under the Bush Administration. He says there has to be a policy that’ attacks the problem at all levels: cultivation, the process of turning it into heroin, the chemists, traffickers, and people protecting traffickers.

Holbrooke’s office did not respond to questions about the effectiveness of their policy, or the State Department OIG’s criticism by press time.

Tom Gregg, a fellow on the Afghanistan regional project at the Center on International Cooperation, said that moving away from eradication is acknowledging the complexity of the issue. The CIC is part of New York University, where Holbrooke’s senior advisor Barnett Rubin is a director of studies and senior fellow on Afghanistan.

“Fundamentally it’s not as dreadful as an eradication policy,” Gregg said.

The source of drug trafficking and its connection to terrorism dates back to the late 1970s after the collapse of the Afghan state during the Soviet-influenced communist coup. Afghan political-military leaders allied with businessmen engaged across many trades including arms dealing and drugs. Businessmen depended on the strongmen, presumably like the Taliban, and then in exchange gave them money.

The UNODC said that the Taliban and “other anti-government forces” made $50 million to $70 million by charging farmers something like at 10 percent fee on their crops. Also, levies imposed on opium processing and trafficking may have raised an additional $200-$400 million. In addition to revenue, drug traffickers provide insurgents material support, including vehicles, weapons, and shelter.

It’s not so easy to go back now, however. The World Bank’s Department for International Intelligence describes the nuances of trying to reverse the proliferation of poppy farming amid the continuing/escalating turbulence. Security incidents in Afghanistan have increased every year since 2003, and in 2009 there was another sharp rise in security incidents.

Meanwhile, some farmers have lost the skills to live off of crops – raisins (See DII report pg. 15) are just one example – and therefore the comparative advantage has gone down. Consequently, switching a farmer back to such benign crops becomes a chore.

So too is it difficult to pin down the demographic that is impacted by eradication. Rubin and others in the Holbrooke camp underscore the dire economic situation for those who would lose their incomes and the anti-American sentiment eradication creates, thus fueling insurgency. Schweich says that it is in part misleading, as farmers who grow poppies don’t do so out of need.

“It’s not poverty that is driving this, it’s greed in most cases,” he said.

A 2008 UNODC report does say that poverty is not a driving factor in creating an opium boom; rather it is more a combination of under-resourced governments and ongoing insurgencies. Data from the NODC shows that poppy growing in Afghanistan exploded after 9/11 to its record high of 193,000 hectares in 2007, before beginning to decline again.

Now the poppy harvest is decreasing for the third year in a row, only the most recent one coming under the Obama administration. And the decline under Obama is largely due to a naturally-occurring fungus that has destroyed opium crops.

Though Afghanistan produced 90 percent of the world’s opium, the vast majority of farmers grow something other than poppies. Only 6.4 percent of the total population or 12.9 percent of the rural population was involved in poppy cultivation (UNODC survey, pg. 76).

What’s more, in Afghanistan, it’s actually against the Constitution to grow or cultivate poppies. So permitting poppy growing could send the wrong message to other Afghan farmers who are not growing poppies, Schweich suggests, in essence telling farmers it’s OK to violate the constitution, and it undermining the very rule of law they’re trying to establish.

“It’s a preposterous mixed message with no chance of long-term success,” he said.

Gregg admits though there are a number of contradictions in the international approach, such as the inequitable distribution of the foreign dollar in Afghanistan. The insurgency is in the South and Southeast, he says, where a lot of the foreign aid goes. “In some ways is rewarding bad behavior,” Gregg said. Some of what the military needs to do is to identify the swing provinces, he recommended, first award areas that aren’t growing poppies.

It may be that the previous policy of eradication – which could only be executed with force-protected, ground-based eradication and not aerial sprays – could be done better. But it was not in and of itself a bad policy, according to Schweich.

“The central poppy eradication force was inefficient. There’s no doubt about that. However, an eradication component to a comprehensive counternarcotics policy remains essential,” he said.