"The cross-border flow of money and guns into Mexico from the United States has enabled well-armed and well-funded cartels to engage in violent activities. They employ advanced military tactics and utilize sophisticated weaponry such as sniper rifles, grenades, rocket-propelled grenades and even mortars in attacks on security personnel. DTOs have openly challenged the GOM through conflict and intimidation and have fought amongst themselves to control drug distribution routes. The results led to unprecedented violence and a general sense of insecurity in certain areas of the country, particularly near the U.S. border. Between January and September 2009, there were 5,874 drug-related murders in Mexico, an almost 5 percent increase over 2008 (5,600)."

Source

"International Narcotics Control Strategy Report: Volume I, Drug and Chemical Control" (Washington, DC: US Dept. of State Bureau for International Narcotics and Law Enforcement Affairs, March 2010) p. 432.
http://www.state.gov/document…