RIO BRAVO, Mexico, Dec 11 (Reuters) - Mexican soldiers fan out across a desert highway and Hummer military vehicles train their automatic weapons on run-down buildings in a show of force against drug cartels in this dusty U.S. border town.
President Felipe Calderon's year-long army crackdown on drug gangs along the border and throughout much of Mexico has scored clear successes, disrupting smuggling routes and even forcing up the price of cocaine on U.S. streets.
But in Rio Bravo, the cartel gunmen are still so bold that they shot dead a well-known local politician in broad daylight outside his family's restaurant last month.
The government sent almost 3,000 troops and federal police to this area southeast of McAllen, Texas after the killing of Juan Antonio Guajardo, a former federal lawmaker who accused local state politicians of being on the payroll of the infamous Gulf Cartel.
Few feel any safer in northeastern border towns where the cartel remains strong and police are often involved in smuggling.
"Any hope we had for change died with the man they killed, the only one willing to speak out, Juan Antonio Guajardo," said a local leader of the Workers' Party that Guajardo represented. "We've been silenced, we've been told who's boss around here."
To acclaim in Washington, Calderon extradited Gulf Cartel leader Osiel Cardenas in January to face trial in the United States and has sent thousands of troops to the northern state of Tamaulipas that the gang dominates.
In October, police seized 11 tonnes of cocaine after a gun battle with drug smugglers at a Gulf of Mexico port. It was Mexico's biggest ever drug bust at the time.
But on Nov. 29, a group of hitmen riding sports utility vehicles and wielding shotguns gunned down Guajardo and five others, including his bodyguards, in Rio Bravo.
A source close to the Gulf Cartel said the group was still very much on its feet despite the government offensive.
"The operations have had little impact, they haven't damaged the cartel's structure or its operation, only forced it to change tactics and smuggling routes," the source said.
Such has been the government's emphasis on fighting the Gulf Cartel that some politicians have criticized Calderon for not doing more to break up Mexico's other big cartel: an alliance of smugglers from Sinaloa state headed by the country's most-wanted man, Joaquin "Shorty" Guzman.
While cocaine prices have risen on U.S. streets as supply from Mexico drops, the Gulf Cartel has expanded into central and southern Mexico and into Texas.
Even the once quiet oil port of Ciudad del Carmen is a new logistical base for moving South American cocaine northward. "The cartels, especially the Gulf Cartel, have set up drug dealing here and there is a criminal network operating at least since last year," said Patricio Patino, deputy intelligence chief at the federal public security ministry.
In response, Mexico and the United States plan to spend $8.4 billion on a three-year assault against the drug gangs from next year, with $1.4 billion pledged by Washington.
The plan will improve Mexico's range of anti-drug tools with new helicopters, aerial surveillance equipment and detection gear.
But drug trade experts say the government must also cut off the cartels' finances, do more intelligence work and attend to Mexico's social ills.
"When there are no jobs or future for young people, drug cartels can take over towns and cities and no amount of soldiers will push them out," said Jose Maria Ramos, a security expert at the Tijuana-based research institute Colegio de la Frontera Norte. (Additional reporting by Magdiel Hernandez in Nuevo Laredo and Anahi Rama in Ciudad del Carmen; Editing by Kieran Murray)
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