25 January 2012 Last updated at 11:29 ET

Q&A: Mexico's drug-related violence

Mexican President Felipe Calderon launched his crackdown on the drug cartels in December 2006.

Since then, many thousands of people have been killed.

What is the scale of the violence?

The Mexican government issued partial figures on 11 January 2012. These showed that 12,903 people had been killed in violence blamed on organised crime from January to September 2011. Added to the previous overall total, this means that 47,515 people have died in the five years of Mr Calderon's presidency. Although there is no breakdown, the victims include suspected drug gang members, members of the security forces and those considered innocent bystanders.

Where are the worst-hit areas?

Violence was first concentrated in Mexico's northern border regions, especially Chihuahua, as well as Pacific states like Sinaloa, Michoacan and Guerrero. Ciudad Juarez (just across from El Paso in Texas) was the most violent city. In 2010, some 3,100 people were killed in Juarez, which has a population of more than a million.

But since 2010, violence has spread to other regions, including Nuevo Leon and Tamaulipas states. One of the focal points for violence has been Mexico's third-largest city, Monterrey.

2011 also saw new areas hit. For example, Veracruz on the eastern coast saw a series of mass killings.

So is the government losing the drugs war?

The Mexican government argues that the violence shows that its aggressive strategy is forcing gangs to split and take on one another, often in increasingly brutal and gruesome fashion. Officials say record amounts of drugs have been seized, and senior cartel leaders jailed or killed in operations.

They also note that the rise in murder from 2010 to 2011 was 11% - much lower than previous increases. For example, a year earlier killings rose 70%.

But aren't there concerns about the military's involvement in the drugs war?

More than 50,000 troops and federal police are actively involved in the fight against the cartels. Human rights activists have expressed concern that troops are ill prepared for policing duties. The military's lack of accountability is also an issue, as soldiers have been subject only to military justice. In July 2011, the Supreme Court ruled that soldiers should be tried in civilian courts.

How serious is corruption within the police?

Very. One reason why the government has deployed the army so extensively is that it feels the police cannot be trusted. Drug cartels with massive resources at their disposal have repeatedly managed to infiltrate the underpaid police, from the grassroots level to the very top. Efforts are under way to rebuild the entire structure of the Mexican police force, but the process is expected to take years.

How much support is there for the government's policy?

Opinion polls suggest that public backing is declining as the violence continues unabated and calls for a rethink have grown. Mr Calderon, while stressing he is against legalising drugs, has said he would be open to a debate on the issue.

Mexico holds its presidential election in July 2012 and violence will be a key issue for voters.

Who are Mexico's powerful cartels?

The cartels control the trafficking of drugs from South America to the US, a business that is worth an estimated $13bn (£9bn) a year. Their power grew as the US stepped up anti-narcotics operations in the Caribbean and Florida. A US state department report estimated that as much as 90% of all cocaine consumed in the US comes via Mexico.

Alliances shift between the main gangs as they vie for control of trafficking routes. Experts argue that there are now two main players: the Sinaloa (also known as the Pacific) Cartel and Los Zetas. US security firm Stratfor, in a January 2012 report, said that Los Zetas were now the biggest cartel in terms of geographic presence.

To what extent is violence spilling into the US?

Most of the violence remains firmly on the Mexican side of the border, according to an August 2011 report by the US National Drug Intelligence Center.

The report said that major Mexican-based transnational criminal organisations (TCOs) would continue to dominate wholesale drug trafficking in the US for the foreseeable future and will further solidify their positions through collaboration with US gangs.

What has been the US response to the drug trafficking and violence?

In March 2009, the US government announced that it would step up efforts to disrupt the illegal flow of weapons and drug profits from the US to Mexico - a key demand of the Mexican government.

However, in November 2010, a US justice department report said that US efforts to tackle gun-smuggling lacked focus, with not enough intelligence-sharing between US agencies and with their Mexican partners.

And a Senate report in June 2011, Halting US Firearms Trafficking to Mexico, suggested that some 70% of firearms recovered from Mexican crime scenes in 2009 and 2010 and submitted for tracing came from the US.

The US, Mexico, Central American nations, Haiti and the Dominican Republic form the Merida Initiative - a $1.5bn scheme that aims to help by providing equipment and training to support law enforcement operations.