Mexico's war on drug gangs pits the army and police against former elite anti-drug commandos who now work for drug bosses.

BY SUSANA HAYWARD
Knight Ridder News Service

NUEVO LAREDO, Mexico - As the Mexican government dispatches federal police and soldiers to cities along the U.S. border to stanch a war between rival drug gangs, the major challenge they may face are the Zetas.

These former Mexican elite commandos, trained to combat drug traffickers, have switched sides. Prosecutors say Zetas are accused in more than 200 killings and now control much of the illegal activity in this swath of northern Mexico, severely hampering police on both sides of the border.

No one knows precisely how many former commandos are in the employ of drug cartels. But their work is well known in the cities of Nuevo Laredo, Reynosa and Matamoros, hard against the U.S. border, where they control neighborhoods and watch for any outsiders who might be government spies.

They're thought likely to have been responsible for the execution Jan. 20 of six prison employees near the federal maximum-security prison at Matamoros. And it was the fear that they were plotting to bust out jailed drug traffickers that prompted a crackdown Jan. 15 at the La Palma prison in central Mexico, where one of the country's best-known drug bosses, Osiel Cardenas Guillen, was housed.

SHOULD BE WORRIED

''There's no antecedent to this type of phenomenon,'' said Jorge Chabat, a political analyst who studies the drug trade. ``The majority of other criminals don't have this type of training. They move like guerrillas, appear in one city and then another. They're not a traditional army . . . Their violence is sophisticated, and that should worry the Mexican government.''

The attorney general's office for years dismissed the Zetas as decimated. But officials now acknowledge that curbing them is a main goal of the current crackdown, in which hundreds of federal agents have been sent to border cities and dozens of inmates have been transferred within the correction system to break up prison gangs.

Maximum security prisons at La Palma, outside Toluca, and Matamoros remain under virtual military occupation, and Cardenas, for whom the Zetas are thought to work, has been transferred to Matamoros. Another major drug boss, Benjamín Arellano Félix, remains imprisoned in La Palma.

Whether the government can beat the Zetas is an open question. Many think the Zetas are better trained and better armed than their government opponents.

When 100 soldiers encountered a reported eight drug traffickers Jan. 28 in the state of Sonora, the troops withdrew. News reports quoted army commanders as saying, ``They have better weapons. We could do little.''

Fear of the Zetas is palpable along the border. ''Everyone's afraid,'' said a businessman from Laredo, on the U.S. side. ``Business is down on both sides. You don't mention the Zetas or traffickers. Word gets around.''

''You say one wrong thing to the wrong person and you and your family end up dead in a ditch,'' one housewife said.

Federal police agents, on patrol in Reynosa, south of Brownsville, Texas, asked that they not be identified. ''We don't want to die,'' one said. But they also said they believed they would overcome the Zetas eventually.

''Sooner or later, something's got to give. They'll have to come out to resume their dealings. We call it the cockroach effect: They run, but come back to the place where there's food,'' said an officer who helped capture Cardenas in Matamoros in 2003.

STAY AWAY

Last month, the U.S. government warned Americans to stay clear of many parts of border cities. According to the State Department, 27 Americans have been kidnapped in the past six months, a majority in Nuevo Laredo. Two of them were killed, 14 were released and 11 are still missing.

The Zetas are just one sign of the strength of Mexico's drug gangs even from behind bars. The military takeover of La Palma found that drug traffickers jailed there had set up a parallel administration for the prison, with access to cellphones and other sophisticated communications.

La Palma had become lax, officials said. X-ray machines and metal detectors didn't work. Officials said that guards, who make $400 to $900 a month, allowed weapons and drugs in.

La Palma wasn't the only place where drug gangs operated. On Feb. 6, federal authorities arrested the head of President Vicente Fox's travel staff, Nahum Acosta, for allegedly passing information to a drug cartel about Fox's travel agenda. Acosta, 42, has denied the charge.

POLICE PRESENCE

Meanwhile, Mexican officials said they would continue the crackdown until they regain control from the drug gangs.

More police and soldiers now range along a 200-mile swatch of northern Mexico from Nuevo Laredo to Reynosa and Matamoros. Police say residents near the border welcome the presence of federal police but wonder if violence will resume when they leave.

Outside the Matamoros prison, guards in ski masks keep a tight cordon, allowing no visitors to pass.

''It's a fight that will never end,'' one police captain said. ``There's always something new. We have reports the Zetas have moved. They're all over, but this is their territory. The question is, what happens next?''