Violence between rival drug smuggling organizations in Mexico has not, for the most part, spilled over the border into the United States, but the danger is increasing, according to a report, titled: Drug Cartels: The Growing Violence in Mexico. The threat comes from the criminal gangs, as well as terrorists who might collaborate with them.

Mexican police in Monterrey

Recent news reports have told of shoot-outs on the streets of some Mexican border towns and the beheading of police officers as far south as the Pacific resort city of Acapulco. The U.S. ambassador to Mexico has warned travelers from the United States to be cautious when visiting the country.

But Fred Burton, author of the report by the Austin, Texas-based Stratfor (Strategic Forecasts) risk analysis firm, says the murder of journalists and threats against news media outlets in many Mexican border towns has made it difficult to see the whole picture.

"From our perspective, the sheer amount of violence and corruption is probably under-reported, because we are not getting accurate and open press out of Mexico about what is actually taking place," said Fred Burton.

Burton says the rampant violence south of the border is the result of competition between Mexico's three major drug cartels over the lucrative drug trafficking business. The smugglers use numerous routes along the 3,000-kilometer border to move marijuana, methamphetamines, heroin and cocaine, which mostly comes from Colombia.

He says the Mexican criminal organizations are establishing a presence on the U.S. side of the border, as well.

"We do have intelligence information that there has been a large measure of transit of drug cartel members, narco-terrorists, for lack of a better term, that have crossed into the United States, and have used, for example, Texas and Arizona as safe havens," he said. "Then there is also intelligence that some of the murders that have taken place inside Texas, specifically, have been perpetrated by various cartel members."

Burton says human-smuggling criminal organizations are working with drug smugglers in some cases, using their routes and methods for bringing illegal immigrants across the border. He says U.S. officials worry that, one day, these smugglers, so-called coyotes, will take money in exchange for smuggling terrorists or even weapons across the border.

"This is very challenging from a law enforcement perspective, because, not only do you have to be on the lookout for drug-runners, but you have to be on the look-out for 'coyotes,' or 'mules' bringing in other kinds of contraband, which could include weapons of mass destruction," pointed out Fred Burton.

Fred Burton says Mexico's president-elect, Felipe Calderon, will face a very difficult challenge from his nation's drug cartels when he takes office in December. He says the traffickers have billions of dollars to buy weapons and corrupt police officials, and that some highly trained former military commandos are now working with the criminal organizations. He says stepped up law enforcement efforts on both sides of the border will be necessary to contain the threat.