One of Mexico's most violent drug gangs has turned against its former armed wing in the latest outburst of killings on the U.S. border to test President Felipe Calderon's overstretched army crackdown.
Black-clad enforcers from the Gulf cartel over the border from Texas are attacking their erstwhile allies from the "Zetas" gang with automatic weapons and grenades in towns near the Laredo-Brownsville area in a fight over some of Mexico's most lucrative trafficking routes into the United States.
Rival gunmen, their gangs' initials emblazoned on their clothes and their flashy SUVs, have killed more than 100 people in the past two weeks along Mexico's northeastern border, local politicians say.
Navy special forces in helicopters have moved in, firing on gunmen from the air in the worst escalation of violence in the area since Mexico's top trafficker Joaquin "Shorty" Guzman made an unsuccessful push for the south Texas border in 2005.
"We are in a war zone. This is our Iraq, this is our Afghanistan," said a town councilor in Rio Bravo, across from McAllen, Texas, who declined to be named for safety reasons.
Mexico's drug war has killed some 18,600 people, mainly cartel members and police officers, since Calderon took power and launched an army crackdown on traffickers in late 2006. The rampant violence worries Washington and foreign investors.
The Gulf cartel's home turf in northeastern Mexico had been relatively calm, but tensions between the cartel and the Zetas, who split away in early 2008, broke into a full-scale war last month, U.S. and Mexican anti-drug officials say.
Made up of elite former soldiers who switched sides to join the Gulf cartel in the 1990s, the Zetas are now trying to run their own trafficking operation and are charging their old bosses taxes to use their routes. The Gulf cartel's recent killing of a Zeta leader may have sparked their battle.
Hitmen have strung up bodies over roads in manufacturing towns along the border and held gunfights in shopping centers and on city streets. The United States has closed its consulate in Reynosa until further notice.
Banners were hung across Reynosa on Wednesday telling the army to leave and vowing the Gulf cartel and its allies will defeat the Zetas.
"You fight poison with the same poison," read the banners, signed "Cartels of Mexico United against the Zetas."
FEW TROOPS ON THE GROUND
Violence has also spread to the wealthy industrial city of Monterrey, where gunmen attacked a string of police stations last weekend and fought the army in surrounding towns.
The attacks come as drug violence escalates in Ciudad Juarez, across from El Paso, Texas, and throughout Mexico, bringing unwelcome media attention as U.S. college students head to Mexican beaches for their annual "spring break."
Factories on the border run by U.S. and Asian manufacturers are operating normally but one security consultant said he is receiving worried calls from U.S. executives about the deteriorating security situation.
"We do have clients who are thinking, where else can we go, Central America, the Caribbean?" said Fred Burton, a security expert at Texas-based consultancy Stratfor.
Some U.S. companies, attracted to Mexico by low labor costs, have frozen investment in border factories, particularly in Ciudad Juarez, Mexico's bloodiest front in the drug war.
Even with the jump in violence around Reynosa, few troops are patrolling the area, angering middle-class Mexicans whose support is crucial for Calderon's drug war.
The armed forces are already stretched, hunting down traffickers from Mexico's Caribbean coast to central and western states and all along the northern border to Tijuana.
Meanwhile, Gulf cartel members and Zetas have set up their own checkpoints to search for rivals and intimidate poorly-paid local police officers who lack the weaponry to confront them.
"It's as if the government doesn't know what to do. They have no plan to regain security and we feel enormously vulnerable," said Cirila Quintero, a sociologist at the Colegio de la Frontera Norte research institute in Matamoros.
To acclaim in Washington, Calderon extradited Gulf cartel leader Osiel Cardenas in January 2007 and the kingpin was sentenced to 25 years in prison in Texas last month.
But the cartel remains a powerful force under his brother Antonio Ezequiel Cardenas, nicknamed "Tony Tormenta" ("Tony the Storm"), controlling about a third of all narcotics shipments into the United States.
The Zetas, named after a police code for high-ranking officers, may number more than 100 but copycat killers claiming the same name make it hard to estimate their actual size.