The drug war has grown to rival the conflicts in Iraq and Afghanistan, as the scale of violence, spending, and weapons in Mexico and Central America have made it one of the most dangerous areas in the world, say US military officials.

Even as the Pentagon struggles with how best to help the Mexican government, US drug users are funding the cartels, senior US commanders told the Senate Armed Services Committee, enabling narcotics gangs to build mini-submarines that they use to transport millions of dollars worth of drugs with every trip.

American consumers of narcotics drive the drug trade, and US weapons arm narco-criminals, says Andres Martinez, a fellow with the New America Foundation think tank.

US drug users contribute roughly $40 billion a year to Latin American cartels, Admiral James Winnefeld, head of the US Northern Command, in charge of US homeland security, added in testimony. The amount of US money that goes to Mexican cartels is so considerable that “if you ranked it among the world’s militaries, it would come into the top ten.”

On the other side of the fight, the US spends about $6 billion per year on interdiction and international efforts, according to the Office of National Drug Policy.

But that's only a small part of the actual cost, Winnefeld noted. "The annual direct cost for treatment, prevention, interdiction, and local law enforcement of drug abuse exceeds $52 billion," he explained. Indirect costs, including lost productivity and the impact on the criminal justice system, reach "nearly $181 billion annually."

Scale of the violence

Transnational criminal organizations “conduct illicit trafficking with near-impunity and are causing unprecedented levels of violence,” said Gen. Douglas Fraser, head of US Southern Command, which has responsibility for US military partnerships in Latin American and the Caribbean.

The so-called Northern Triangle of Guatemala, El Salvador, and Honduras “is the deadliest zone in the world outside of active war zones,” Fraser added.

In the past four years, as many police and soldiers have died in Mexico alone as in Iraq and Afghanistan.

Collateral damage is also comparable: since 2006, nearly 35,000 Mexicans were killed in drug-related violence, compared to 21,000 Afghan civilians killed in the war during that same period of time.

Given the staggering figures, the violence is increasingly liable to spill over into the United States, the two commanders warned.

Arming the cartels

The United States bears some responsibility for this, Winnefeld told the committee. “There are a number of weapons that are flowing south across our border,” he said.

The Pentagon is concerned, too, about the increasing sophistication of narco-criminals' equipment, such as night-vision goggles. “I’m not really sure where they come from,” Winnefeld said. Narco-traffickers are also using “heavily-armored vehicles that are more and more resistant to the types of weapons that the Mexicans are using,” he added.

Latin American drug gangs are using fully submersible mini-submarines to move cocaine from South America to Central America. These vessels are “very difficult to detect,” Fraser said, as they transit along the Pacific coast from Ecuador and Colombia to the Guatemala-Mexico border. These submarines, built in the jungles of Colombia and Ecuador, may cost $3 to $4 million to produce, “but one transit will equate to about $70 to $80 million of return,” he added.

Nearly all of the cocaine destined for the United States crosses through the Mexico-Guatemala border.

Political challenges

Even in the face of enormous threats, the Mexican government is wary of openly accepting US military aid and training.

Diplomatic cables posted by Wikileaks revealed the US embassy in Mexico criticizing the Mexican military for failing to act on intelligence tips, causing an outcry in Mexican political circles that led to the resignation of the US ambassador to Mexico last month.

The cables brought to light, too, that US embassy intelligence officials were deeply involved in some of the more stunning takedowns of drug cartel heads – not the sort of information that Mexican leaders were anxious to have come to light.

US officials “were criticizing the Mexican army at a time when Mexicans perceive that they are dying on behalf a problem that they consider a US issue,” says Mr. Martinez.

After the Wikileaks revelations, Mexican political leadership retreated somewhat from working with the US, after a couple of years of relatively close partnerships, Martinez says.

Pentagon officials acknowledge this tension, but point out that US troops have learned some irregular warfare techniques in Iraq and Afghanistan that they are anxious to pass along to their Mexican counterparts. US military forces have already shared lessons in “How do you do planning, how do you do special operations, and how you carefully observe human rights," Winnefeld says.

For now, however, Mexican soldiers and police are “up against a sophisticated, ruthless, and very well-financed threat,” Winnefeld warned, adding, “things are probably going to get worse before they get better.”