In January 2009, retired Gen. Mauro Tello Quiñones took command of a police unit charged with combating drug-related violence in the popular Mexican tourist destination of Cancún.
The assignment lasted just one week. In early February, Tello and two aides were kidnapped and killed. Before murdering Tello, the assailants broke his arms and legs and tortured him for hours. The incident provoked shock across Mexico, with the governor of Quintana Roo state calling it "truly horrible."
Even by the standards of the violent drug war that has consumed Mexico of late, this crime stood out for its brazenness and brutality. In short, it bore all the marks of an attack by the notorious paramilitary organization known as Los Zetas.
Originally composed of 31 army deserters who went to work for a cartel boss, the Zetas have evolved over the past decade into a sophisticated criminal enterprise with more than 1,000 members. Drawing on military-style skills and a penchant for the gruesome, the group has expanded its illegal activities and established itself as the most feared and destructive player in the Mexican drug trade.
The Zetas have ruthlessly seized market share, waged a bloody campaign against the authorities, and used coercion and bribery to hollow out government institutions from within. Their exploits have spurred the militarization of the Mexican drug trade.
In short, they have done more than any other entity to foster the cycle of violent chaos in which the country is currently trapped. Having begun as hired guns, the Zetas now represent the single greatest threat to the Mexican state.
The Zetas were founded in 1997 amid the dramatic intensification of the Mexican drug trade. During the 1990s, drug trafficking in Mexico became a more lucrative -- and also a deadlier -- profession: more lucrative because U.S. interdiction programs in the Caribbean made Mexico the primary entry point for cocaine and heroin consumed in the United States; deadlier because the rules that once governed the business broke down.
For decades, the Institutional Revolutionary Party (PRI) had overseen a system in which drug kingpins paid bribes and kept violence to a minimum. In return, the PRI protected the cartels and allocated access to the plazas, or drug-running corridors into the United States. As the PRI lost power during the 1990s, this system came apart, and comparative stability gave way to a Hobbesian struggle for the plazas.
The epicenter of this bloodshed was Nuevo Laredo, a city of 350,000 inhabitants that sits directly across the border from IH-35, the chief north-south artery in the United States.
To protect this valuable real estate, Gulf Cartel chief Osiel Cárdenas decided to form an elite paramilitary group that would give him an edge over the rival Sinaloa Cartel. In 1997, he induced 31 gafes, or members of Mexico's Airborne Special Forces Group, to switch sides, and the Zetas -- who take their name from the radio code for "captain" -- were born.
When the Zetas signed on with Cárdenas, they brought with them a set of skills unique in the Mexican drug trade. The gafes were Israeli-trained counterinsurgency specialists with expertise in ambushes, marksmanship, intelligence, intimidation, and other military techniques -- skills they put to good use in their new profession.
The Zetas murdered Cárdenas' competitors, safeguarded his drug shipments, served as his personal protection detail, and became an invaluable asset to the Gulf Cartel.
After Cárdenas was arrested by the Mexican authorities in 2003 and extradited to the United States in 2007, however, the Zetas went into business for themselves. Led by Heriberto Lazcano Lazcano and Jaime González Durán, they eliminated several Gulf lieutenants and forced their way into the upper echelons of cartel leadership.
The Zetas commandeered a large chunk of Gulf operations, embraced new criminal activities -- including robbery, kidnapping, extortion, money laundering, and human smuggling -- and expanded their area of operations to include much of Mexico, as well as parts of Guatemala and the United States.
They also grew numerically. When Cárdenas was arrested, there were around 300 Zetas; as of early 2009, there were somewhere between 1,000 and 3,000. Originally cartel enforcers, the Zetas have now become a full-fledged drug-trafficking organization (DTO) in their own right.
As the Zetas have expanded, they have sought to retain the martial qualities that infused the original band of 31. The group now includes several dozen Kaibiles, Guatemalan counterinsurgency specialists who, like the original Zetas, deserted the army in search of higher pay. The Kaibiles are renowned for their skill and ruthlessness.
Their motto is: "If I advance, follow me. If I stop, urge me on. If I retreat, kill me." The Zetas also continue to recruit among Mexican military personnel -- not difficult to do, as well over 100,000 soldiers deserted between 2000 and 2009 -- and have established training camps where new members receive instruction in assassination, kidnapping, torture, and intelligence techniques.
These courses last three months, and are reportedly so rigorous that a number of recruits have lost their lives.
The military ethos is also evident from the group's command structure, which is divided into five distinct tiers. Los Halcones constitute the lowest tier, gathering information and acting as the "eyes of the city." Los Cobras provide security for drug shipments and Zeta higher-ups.
Zetas Nuevos are the shock troops who carry out the bloody assaults for which the group has become famous. Cobras Viejos are more experienced Cobras in charge of coordinating trafficking and security affairs. Zetas Viejos each control a plaza, and command assistants ranging from computer specialists to money launderers.
Only individuals with a military background can attain the rank of Zeta Nuevo or Zeta Viejo, and the latter group is composed primarily of men who have been with the organization since its inception or shortly thereafter. Military-style discipline governs interactions between the ranks: It has been reported that Cobras are not allowed to fire unless so ordered by a superior.
When the Zetas emerged as their own distinct entity, it marked an epochal shift in the Mexican drug trade. Mexican DTOs had heretofore employed thugs and petty criminals as enforcers. Now a group of well-trained soldiers had taken over a DTO and began to run it as a paramilitary organization.
The implications were soon apparent. The Zetas were the first Mexican DTO to employ a military-grade arsenal, making the jump from the standard AK-47 to shoulder-fired missiles, armor-piercing ammunition, fragmentation grenades, heavy machine guns, and even improvised explosive devices.
Some of these weapons are stolen from the Mexican military or purchased on the black market. Most are bought legally in the United States and smuggled across the border.
Arguably more important, the Zetas were the first to combine this massive firepower with expertise in infantry squad tactics, complex assaults, and other military techniques. The result has been a qualitative escalation in the intensity of drug-related violence in Mexico.
As Fred Burton of Stratfor notes, "Assault rifles in the hands of untrained thugs are dangerous, but if those same rifles are placed in the hands of highly trained special-forces soldiers who can operate as a fire team, they can be overwhelmingly powerful."
Over the past several years, the Zetas have used these capabilities to batter their competition and carry out a string of deadly assaults against Mexican authorities. Tello's murder was just the latest in a series of assassinations by the Zetas.
The group also killed Nuevo Laredo's police chief in 2005 just hours after he took office, and government officials in other Zeta-controlled towns have met a similar fate.
The Zetas regularly attack police stations, ambush government convoys, and wage fierce firefights against rival DTOs as well as the Mexican military. Since 2007, groups of up to 50 Zetas have also orchestrated mass jailbreaks in Tamaulipas, Michoacán, Veracruz, and Durango.
The Zetas have distinguished themselves not only with their audacity, but also with their savagery. Zeta operatives subject their captives to prolonged torture before executing them -- often by decapitation, immolation, strangulation, or other grisly methods.
In one instance, the Zetas stuffed four individuals suspected of working for a rival DTO inside barrels of diesel fuel and burned them to death. Such brutality serves a dual purpose.
Torture allows the Zetas to elicit information from their victims, while graphic execution scenes send a chilling message to competitors. As political scientist George Grayson comments, "Even mentioning the word 'Zeta' conjures images of castrations, decapitations, and immersion in vats of lye."
The Zetas do not rely on brute force alone. Their skill set has also allowed them to undertake more sophisticated operations.
The group executes infiltration attacks with precision. In 2007, for instance, Zetas masquerading as soldiers gained access to two police stations and executed seven government officials.
Their technological capabilities are equally impressive, and the Zetas have coordinated kidnappings and assassinations by tracking their rivals' cellphone signatures. Similarly, the Zetas are adept at the arts of propaganda and intimidation.
They publish lists of police officers to be targeted for assassination, demand that local newspapers feature extensive coverage of their bloody exploits, and -- borrowing from the Iraqi insurgents --were the first Mexican DTO to post execution videos on YouTube.
According to the Drug Enforcement Administration (DEA), the Zetas have now become "the most technologically advanced, sophisticated and violent" of the Mexican DTOs.
This prowess has allowed the Zetas to dramatically increase their market share. It has also permitted them to neutralize the very institutions that are meant to restrict their activities.
Corruption has long been central to the drug trade, and the Zetas have used a combination of inducement and brutality to undermine local and state police forces.
In some cities, they spend up to 3 million pesos (around $230,000) per week on bribes, and threaten or viciously murder those who refuse to accept.
The 2005 killing of Nuevo Laredo's chief of police was especially important in this regard, sending the message that honest police work would not be tolerated. These tactics have allowed the Zetas to gain the assistance of thousands of police officials and led to a drastic reduction in police effectiveness in areas under Zeta control.
This formula of plata o plomo ("money or lead") can also be useful in co-opting segments of the population as a whole. While Zeta violence provides a reminder of what awaits those who oppose the group, the organization uses proceeds from drug sales to buy citizen loyalties.
The Zetas donate food, bicycles, clothing, and toys to impoverished neighborhoods, and members of the group style themselves in the image of a popular 19th-century Mexican bandit known as "The Angel of the Poor." Given the pervasive poverty and social alienation that afflict Mexico, these tactics can be quite effective.
Young boys proclaim that "I want to be Zeta," the Washington Post reports, and recipients of the group's largesse have said that "we are all Zetas." In other words, the Zetas do not just use violence to batter the Mexican state. They exploit poverty, corruption, and failures of governance to weaken it in more subtle ways, as well.
Indeed, despite the support they have purchased from some marginalized sectors, the Zetas have had a profoundly destructive impact on Mexican affairs.
The group's appearance in a new locale invariably elicits a profusion of bloodshed. The dramatic escalation of drug-related violence since 2006 -- Mexico has suffered well over 10,000 drug-related murders during this period -- is widely attributed to the concurrent expansion of Zeta influence.
Numerous areas in which the group operates have become so violent that they are effectively beyond government control. As a DEA agent told me in 2008, the Zetas have turned large chunks of Mexico into something "between Al Capone's Chicago and an outright war."
Perhaps more troubling, Zeta exploits have touched off an arms race within the Mexican drug trade. Other DTOs have formed their own paramilitary organizations, and groups like Los Pelones, Los Negros, and Las Fuerzas Especiales de Arturo now serve various cartels.
Like the Zetas, these organizations are composed largely of former police and armed forces personnel, and they utilize military tactics along with a bevy of advanced weapons.
They have also sought to replicate the Zetas' astonishing brutality: Torture, dismemberment, and assassination are now stock tactics of the Mexican narcotics business.
"We're seeing a transition from the gangsterism of traditional hitmen to paramilitary terrorism with guerrilla tactics," says Luis Astorga, an expert on drug trafficking. Innovation has spurred imitation, with devastating consequences for Mexico.
All this has put the Zetas squarely in the crosshairs of the Mexican government. Felipe Calderón has made counternarcotics the centerpiece of his presidency, deploying over 40,000 soldiers in a bid to cripple the cartels and restore internal stability.
Defeating the Zetas is a top priority for Calderón. He has likened the group to al-Qaida, and during 2007-08, Mexican authorities placed special emphasis on targeting the Zetas. González Durán was arrested in November 2008, and another top lieutenant, Gregorio Sauceda Bamboa, was apprehended in early 2009.
Mexican authorities have also broken up corruption rings linked to the Zetas and seized large caches of drugs, money, and weapons.
Calderón's offensive has injured the Zetas, but it has hardly defeated them. Far from giving ground in the face of government operations, the Zetas have launched their own bloody campaign against the military. In December 2008, the Zetas abducted eight soldiers in the southern state of Guerrero and later displayed their headless bodies on YouTube.
Since then, they have killed Tello and numerous other military officials. Calderon is betting that the army can restore order where the police cannot.
The Zetas, in turn, are seeking to show that even trained military professionals are no match for their skills. So far, the Zetas are holding their own in this battle, and their attacks have taken a steep toll on military morale.
Calderon's counternarcotics program has also been plagued by the same structural weaknesses that the Zetas so ruthlessly exploit. Corruption within the police and military has apparently allowed the Zetas to escape the worst of several government strikes, while human rights violations by the authorities have hurt public enthusiasm for Calderon's crusade.
The Zetas are keenly aware of this dynamic. They often seek to provoke the armed forces into overreacting and thereby harming the civilian population. Along with other DTOs, they have also sponsored anti-military demonstrations in several Mexican cities.
If anything, the Zetas have become more ambitious of late. Since 2007, they have moved into Guatemala in an effort to dominate the land-based smuggling routes running north from Colombia. Guatemalan officials warn that the Zetas are setting up bases in secluded jungle areas, and the group is responsible for a number of deadly firefights on Guatemalan soil.
The Zetas are also looking north. The group recruits new members on the U.S. side of the border, and Zeta affiliates have been implicated in murders across the southern United States. In mid-2008, Zetas posing as a Phoenix SWAT team murdered a rival trafficker and exchanged fire with real police arriving on the scene.
Later that year, the FBI warned that the Zetas were stockpiling ammunition in southern Texas and preparing a "full tactical response" should U.S. authorities interfere with their operations. On the heels of a meteoric rise within Mexico, the Zetas are now embracing a broader international agenda.
The Zetas cannot maintain their current ascent indefinitely. By inspiring emulation among their competitors, the Zetas have ensured that the challenges they face from rival DTOs will only increase with time. Other organizations will adapt and become more deadly, and the Zetas' violent pre-eminence will eventually wane as a result.
For now, however, the Zetas represent the highest evolution of organized crime in Mexico. They have used their distinctive capabilities to outclass the competition, batter the authorities, and relentlessly exploit Mexico's institutional and social weaknesses.
The group has taken on an international dimension by moving into Guatemala and the United States, while at home, it constitutes the foremost challenge to internal stability and the Mexican state.
As Calderón's recent experience has shown, taming the Zetas will be no easy task.
Within Mexico, it will necessitate not only strengthening the police and military, but also addressing the deep-seated issues -- corruption, weak governance, and poverty -- that abet Zeta activities and fuel the drug trade as a whole.
Due to the increasingly transnational nature of the Zetas and their profession, it will also be necessary to broaden multilateral cooperation between the various affected countries and to grapple seriously with those problems -- namely U.S. demand for narcotics and cross-border gun smuggling -- that transcend Mexico's frontiers.
Some of these imperatives may be more easily met than others. Under the Merida Initiative, a three-year program launched in 2008, the United States has pledged roughly $1.6 billion in aid for counternarcotics programs in Mexico and Central America.
The initiative represents a major expansion of U.S. counter-drug assistance to these countries. With its theme of "co-responsibility," it also constitutes an acknowledgment of the need for multinational solutions to a transnational dilemma.
As the nation currently most threatened by drug violence, Mexico will receive the vast majority of Merida funding, which will go primarily to training and equipping Mexican security personnel and promoting cross-border intelligence sharing and law enforcement cooperation.
When added to the $7 billion that Calderón has set aside for counternarcotics over the same period, this aid should bolster Mexican security and interdiction capabilities and thereby increase the pressure on groups like the Zetas.
Yet the Merida Initiative is hardly a panacea. There are concerns that the program focuses too much on security and interdiction and too little on anti-corruption, human rights, and institutional reform. The initiative devotes more than 80 percent of first-year funding to the former concerns and less than 20 percent to the latter.
More broadly, Mexico's institutional deficiencies are so entrenched that they would take years to correct even if the cartels weren't actively attacking the Mexican state. Finally, while the Obama administration has pledged to tackle issues like gun smuggling and U.S. domestic drug consumption, lasting solutions to these problems are nowhere in sight.
If "co-responsibility" turns out to be a catchphrase rather than a meaningful watchword, there will be little chance of making sustainable gains against Mexico's powerful DTOs.
At best, the Merida Initiative and Calderón's counternarcotics programs represent the beginning, rather than the end, of a long struggle to reduce drug-related violence in Mexico.
The Zetas will only be defeated as part of a persistent, holistic, and multilateral approach to the drug trade. The responsibility of the policymakers is to craft, and stick to, a strategy equal to this task.
Hal Brands is the author of "From Berlin to Baghdad: America's Search for Purpose in the Post-cold War World" (2008). He recently received his Ph.D. in History from Yale University, and is completing a history of Latin American politics during the Cold War. He works as a defense analyst in Washington, D.C.