The most popular instruments of robbery, torture, homicide and assassination in this violence-racked border city are imported from the United States.
"Warning," reads the sign greeting motorists on the U.S. side as they approach the Rio Grande that separates the two countries here. "Illegal to carry firearms/ammunition into Mexico. Penalty, prison."
The signs have done little to stop what U.S. and Mexican officials say is a steady and growing commerce of illicit firearms in Mexico -- 9-millimeter pistols, shotguns, AK-47s, grenade launchers. An estimated 95% of weapons confiscated from suspected criminals in Mexico were first sold legally in the United States, officials in both countries say.
Guns are the essential tools of a war among underworld crime syndicates that claimed between 1,400 and 2,500 lives in 2005, according to tallies by various newspapers and magazines.
The biggest criminals in Mexico are engaged in an arms race, with an armor-piercing machine gun as the new must-have weapon for the cartels fighting one another for control of the lucrative trade in narcotics, U.S. and Mexican officials say.
In 2005, Nuevo Laredo residents endured the specter of more than 100 suspected drug-cartel executions in their city, and the release of a horrific videotape in which a suspected drug-cartel gunman executes a "prisoner." The city has become a tragic symbol of the gun violence sweeping through the entire country.
"It's obvious where all the arms are coming from," said Higenio Ibarra Murillo, a Nuevo Laredo business owner in the city's historic downtown district. "We don't make any guns or rifles here" in Mexico.
Buying a weapon legally is extremely difficult in Mexico. The country's defense secretary issues all gun licenses -- the wait is a year or more, and the cost about $1,900. Licenses must be renewed every two years.
There are fewer than 2,500 registered gun owners in the entire country. Yet Mexican police confiscate an average of 256 weapons every day from suspects, officials from the attorney general's office said recently.
Javier Ortiz Campos of Mexico's Federal Preventive Police says traces by the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives on weapons confiscated in Mexico often lead to the gun shops, gun shows and flea markets of Texas. The U.S. state has some of the most liberal gun laws in the country and a porous, 1,240-mile-long border with Mexico.
"Over there they even sell guns at Wal-Mart," Ortiz Campos said. The weapons confiscated in Mexico come mostly from U.S. border cities such as Laredo, El Paso and Brownsville, he said. But many come also from Houston and San Antonio.
"We're finding a lot of weapons from Houston, because the buyers get a better price there than at the border," Ortiz Campos said.
Organized-crime groups in Mexico often buy their weapons in bulk via "straw purchasers" in Texas, where there is no limit on the number of firearms a resident can purchase, said a U.S. official who asked not to be named.
Typically, the Mexican buyer will pay a Texas resident $50 to $100 to acquire the weapons, the official said.
In one case, Mexican and U.S. authorities working together traced 80 confiscated firearms to a Mexican national who paid Texas residents to buy weapons on his behalf, the official said.
Police recovered one 9-millimeter handgun last year at the scene of a shootout between officers and suspected drug-cartel hit men outside the Mexican border town of Reynosa. A trace of the weapon by ATF agents led to another Texas man who had bought 160 weapons. That man is facing gun-trafficking charges in the U.S.
Last year, ATF officials in Arizona arrested a man trying to buy 30 U.S. military hand grenades. The man told undercover agents the grenades were intended for drug traffickers in the northern Mexican state of Sonora. In August, a Tucson man was charged with smuggling AK-47s and AK-47 parts into Mexico.
Large caches of weapons routinely turn up here and in other border communities. Twenty assault rifles were seized in Tijuana on Dec. 20; that same day, Mexican army troops in the state of Sinaloa detained a group of men who were armed with five AK-47 rifles and one AR-15 rifle.
In Nuevo Laredo last month, Mexican police stumbled upon an arsenal in the hands of suspected organized crime members that included grenades, semiautomatic handguns and seven AR-15 assault rifles.
No store in Nuevo Laredo sells handguns or rifles over the counter. But if you take a 15-minute walk over the border to Laredo, you'll find the Bushmaster AR-15 rifle on sale at one gun store for $1,199.
The salespeople at the store speak Spanish, but the sign over a display case of semiautomatic handguns is in English: "If guns are outlawed, only outlaws will have guns."
The slogan, popular with U.S. gun-rights activists, certainly seems to apply on the other side of the border. Only one person has a private gun permit in the entire Mexican state of Tamaulipas, which includes Nuevo Laredo. Yet guns seem to be everywhere.
On the impoverished edges of the city, small-time drug dealers protect their investments with semiautomatics. And many law-abiding citizens can tell of an encounter with armed bandits.
Businessman Jose Luis Ortiz Cardenas witnessed an attempted carjacking by armed robbers last year outside a grocery store he owns. And he'll never forget the notorious 2003 shootout a few blocks from the cantina he operates downtown -- the shooting spread to the bridge leading to the United States.
"It was a hail of bullets, federal agents firing at other federal agents, hit men firing at other hit men, with bazookas and everything," the cantina owner said.
Mexican police have, in recent years, confiscated a handful of bazookas from organized-crime groups. Mexican and U.S. officials say a very small amount of military surplus from recent wars in Central America has found its way into Mexico. But U.S. officials say a bazooka recovered recently from suspected drug cartel hit men in Mexico was traced to an Army depot in Arkansas -- the weapon had been deposited there and last accounted for in 1967.
Assault rifles such as the AR-15 and the AK-47 are by far the most popular weapons imported into Mexico by the drug cartels, police official Ortiz Campos said.
The AR-15 is the civilian, semiautomatic equivalent of the M-16 used by U.S. troops since the Vietnam War. The AK-47 was designed by Mikhail Kalashnikov for the Soviet army in 1947. In Mexican street slang both are known as "el cuerno de chivo" -- "the goat's horn" -- for the distinctive shape of their bullet clips.
"For the narco-traffickers, it's like their good-luck charm," Ortiz Campos said. The drug cartels favor the AK-47 for the same reason the Soviet army did: its ruggedness and versatility.
"With that weapon, you can do incredible things," Ortiz Campos said. The AK-47 is not only powerful, it's also idiot-proof, he added. "It will fire underwater. It will fire when it's covered with mud."
The AK-47 appears in several narcocorrido songs about bad men and their adventures. The song "The Terrifying Cuerno de Chivo" by the group Los Incomparables de Tijuana was made into a movie of the same name.
"Its barrel is decorated, the butt and the trigger too," the lyrics say. "Inlaid with silver all around, it's a weapon fit for a man of courage.... It's an instrument of death."
Assault rifles that are sold legally in the U.S. are not fully automated. But officials say that there are gunsmiths in Mexico who are adapting the weapons to make them fully automatic.
"We have found a few in Mexico that have been converted by a machinist," the U.S. official said. "This tells us someone with vast experience in weaponry is working here."
U.S. and Mexican officials say they are also concerned by the presence of .50-caliber machine guns in Mexico. Originally designed as antiaircraft weapons, the guns are used by cartels because they can penetrate armor.
"We think these weapons are used by the cartels to attack each other" rather than the police, Ortiz Campos said.
"Ten or 15 years ago, you rarely saw a .50-caliber weapon" in Mexico, the U.S. official said. "Now they're popping up everywhere."
U.S. officials say their Mexican counterparts are working harder than ever to fight the weapons trafficking. Mexican federal officials cooperate extensively with the ATF in tracing illicit weapons.
"The Mexicans are eager to see prosecutions for gun trafficking go forward in the U.S.," the American official said. "It's a different attitude than in the past."
Still, the gun violence continues to take on new, disturbing dimensions. Television viewers across Mexico were horrified last month by the airing of a video in which members of the one cartel competing for control of the drug trade in Nuevo Laredo torture hit men from another cartel. The video, obtained by the Dallas Morning News, ends with one of the hit men being executed with a shot to the head from a 9-millimeter pistol.
As Nuevo Laredo becomes a war zone, its streets are increasingly empty. For the most part, tourists are avoiding the city, frightened by the kidnapping and disappearance of several Americans here.
"The one consolation we have is that we know it can't get any worse than it is right now," business owner Ortiz Cardenas said. "We've hit rock bottom."