This 2008 photo shows the type of surveillance equipment to be deployed on the border.

Construction has begun on towers for the final version of the virtual fence project in southern Arizona, and project leader Mark Borkowski said Tuesday he’s confident the multibillion dollar will system work well.

Borkowski, executive director of the Homeland Security Department’s Secure Border Initiative program office, said he’s 75 to 80 percent confident in the engineering of the revamped project.

“And I have higher confidence than that that if there were issues, they’d be issues that we could solve,” he said.

Plans call for extending the towers along almost the entire Mexican border by 2014 — at a cost estimated at $6.7 billion.

President Obama has not requested that money, nor has Congress appropriated it — yet.

“Right now, the administration and the Congress are both very interested in continuing this program,” Borkowski said. “What level will it be at — $200 million a year or will it be $2 billion a year? That’s part of the broader national debate about what are the priorities and budgets. But there seems to be a continued interest and priority in this at some reasonable level.”

The virtual fence is designed to use radar and cameras with about a six-mile range, including infrared devices and other technologies, to detect smuggling attempts. The sensors are designed to be able to distinguish people from animals and allow operators to direct Border Patrol agents to intruders.

The first section will cover about 53 miles of Arizona’s border with Mexico, with additional towers, up to 120 feet tall and spaced miles apart, to follow on the remaining 320 miles of the state’s southern border. Virtual fencing then will go up in New Mexico, followed by California and most of Texas.

Borkowski said towers with cameras, radars and sensors and communications gear won’t stop people or substitute for a physical fence. But he said it will tell the Border Patrol where people are entering the country illegally.

“Technology’s not going to secure the borders,” Borkowski said. “Frankly, the personnel fundamentally are going to secure the borders.”

TIJUANA, Mexico – Mexican police say three women who disappeared in the border city of Tijuana were killed by drug traffickers who dissolved their bodies in a caustic substance.

Baja California state investigator Miguel Guerrero says the women — aged 23 to 25 — have been missing since August after they traveled from Mexicali to Tijuana, across from San Diego.

Guerrero says two alleged drug traffickers who were arrested this week confessed to the killings. A third suspect is being sought.

He said in a statement Thursday that the women were killed after one of them argued with one of the suspects in a bar. The victims were smothered, and their bodies dissolved in a drum.

Mexican army soldiers catalog seized weapons in a warehouse at the Secretary of the Defense headquarters in Mexico City. In all, the military has 305,424 confiscated weapons locked in vaults, just a fraction of those used by criminals in Mexico, where an offensive by drug cartels against the military has killed more than 10,750 people since December 2006. The U.S. has acknowledged that many of the rifles, handguns and ammunition used by the cartels come from its side of the border.

MEXICO CITY — Deep inside a heavily guarded military warehouse, the evidence of Mexico’s war on drug cartels is stacked two stories high: tens of thousands of seized weapons, from handguns and rifles to AK-47s, some with gun sights carved into the shape of a rooster or a horse’s head.

The vault nestled in a Mexican military base is the government’s largest stash of weapons — some 88,537 of them — seized from brutal drug gangs. The Associated Press was recently given rare and exclusive access to the secure facility.

The sheer size of the cache attests to the seemingly hopeless task of ever sorting and tracing the guns, possibly to trafficking rings that deliver weapons to Mexico. And security designed to keep the guns from getting back on the streets is so tight that even investigators have trouble getting the access they need.

The warehouse — on a main drag in northeastern Mexico City near the horse racing track — is surrounded by five rings of security. There are two military guards at the door and five more are in the lobby. Inside, another 10 soldiers sort, clean and catalog weapons. Some are dismantled and destroyed, a few assigned to the Mexican military.

The guns are stacked to the two-story ceiling in a warehouse the size of a small Wal-Mart. The rifles lie on 22 metal racks; the pistols hang from metal poles by their triggers.

The cavernous warehouse is impeccably clean, the only smell coming from the coffee the soldiers prepared for their rare visitors. The clash of metal and sounds of the soldiers at work echo off the walls.

The security, bolstered by closed-circuit cameras and motion detectors, makes the warehouse practically impenetrable, said Gen. Antonio Erasto Monsivais, who oversees the armory.

In all, the military has 305,424 confiscated weapons locked in vaults, just a fraction of those used by criminals in Mexico, where an offensive by drug cartels against the military has killed more than 10,750 people since December 2006. But each weapon is a clue to how the cartels are getting arms, and possibly to the traffickers that brought them here.

The U.S. has acknowledged that many of the rifles, handguns and ammunition used by the cartels come from its side of the border. Mexican gun laws are strict, especially compared to those in most U.S. border states.

The Mexican government has handed over information to U.S. authorities to trace 12,073 weapons seized in 2008 crimes — particularly on guns from large seizures or notorious crimes.

But the Bureau of Alcohol, Tobacco, Firearms and Explosives, which handles the U.S. investigations, is at the mercy of local Mexican police for the amount and quality of the information.

“Many of these rural municipalities that may come into a gun seizure … may not even know anything about tracing guns,” ATF spokesman Thomas Mangan said.

A police officer in Mexico submits a description, serial number and distinctive markings of the gun. The weapons are then turned over to the military for storage in one of a dozen armories such as the one in Mexico City.

When U.S. investigators need additional details, as they often do, the request goes back to the original police officer, who must retrieve the gun from a military vault — sometimes hundreds of miles away.

Mexican police must ask permission each time they need to look at a stored gun, Monsivais said. Even if that permission is granted, the investigator cannot go past the metal fencing separating a reception desk and the shelves holding the guns. A soldier has to bring out the requested weapons.

The security, language differences and bureaucracy add up to a painstaking process, said J. Dewey Webb, special agent in charge of the ATF’s Houston Field Division.

“The military does a very good job when the weapons come into their custody of securing them,” he told the AP. “Because of the systems in Mexico, it’s very difficult for us to get in.”

Webb said recent talks between the two countries were beginning to ease access, but also noted other problems.

Many mistakes are made because of difficulty translating technical terms about firearms, Webb said. A Spanish-language version of eTrace, the Web-based method of submitting tracing information, won’t be available until next year.

About a third of the guns submitted for tracing in 2007 were sold by licensed U.S. dealers.

U.S. agents need the information to track the gun back to the manufacturer and determine when it was made and what wholesaler it was shipped to, ATF spokeswoman Franceska Perot said. Agents follow the gun to the local licensed dealer who sold it and determine the buyer.

ATF offices around the U.S. are swamped with tracing requests, trying to determine who actually bought the weapons and whether they were part of a firearms trafficking scheme. The ATF has sent an extra 100 agents to Houston to help unclog the 700-weapon backlog as part of its Project Gunrunner.

The seized weapons are kept in the vaults as long as they are needed as evidence, Monsivais said. Most have been there for years, an indication of how slow criminal investigations proceed and how few crimes are ever solved.

Indeed, the ATF gave the AP data showing the average “time to crime” — the time between when a gun was sold and when it was seized in a crime — is 14 years.

That’s an average of four years longer than guns in American crimes, the ATF said. The older the street age, the harder it can be to track how the gun wound up at a crime scene.

When the criminal investigations are complete, most of the weapons are destroyed and melted down. Some of the more powerful arms, such as M16 machine guns and sniper rifles, are added to the military’s own arsenal. Showpieces are destined for museums.

Most of the guns traced were originally sold by U.S. dealers in border states, with more than half purchased in Texas. Not only does Texas have the most gun dealers of any state, it makes up 1,200 miles of the 2,100-mile U.S.-Mexico border, with many of the established drug and trafficking routes.

Details on the 2008 tracing requests are not yet available.

It’s less clear how cartels are getting military-grade weapons. Amid the shelves of pistols and rifles, there is a 9 mm grenade launcher and a portable shoulder-fired anti-tank rocket launcher.

Such military-grade weaponry represents a tiny fraction of the seized weapons. But Monsivais said he’s most worried about the rising caliber of assault rifles and semi-automatic guns that have been found.

“There are weapons that have a lot of firepower and great penetration, like the .50-caliber Barrett … which can penetrate armored vehicles, body armor, and that normally only militaries use,” Monsivais said.

Thirty percent of AK-47 assault rifles seized have been modified to become fully automatic. He said about three of every 1,000 AR-15 assault rifles have been modified to take .50-caliber bullets, the kind of high-powered ammunition designed for sniper rifles.

“In my experience, I had never seen a modified AR-15 rifle,” Monsivais said. “It’s something new, and it is to a certain extent worrisome that they can have and use this type of weapon.”

Dupnik

Pima County Sheriff Clarence Dupnik said his idea has merit, but he will not press Arizona to challenge a U.S. Supreme Court ruling that makes it illegal for schools to check students’ citizenship.

Still, Dupnik said, checking citizenship when students enroll would remove a flaw in the nation’s border security and could deter immigrants from crossing the border illegally.

Such a move would eliminate some of the area’s social woes, he said, adding that the South, Southwest and West sides of Tucson have prominent social problems that can be attributed to illegal immigration.

Dupnik, citing unnamed sources, pointed specifically to the Sunnyside Unified School District, where he said as many as 40 percent of the students are illegal immigrants.

Sunnyside district spokeswoman Monique Soria said that “the district, by law, does not ask for legal status, and we do not have data on that.

“We would be breaking the law if we did ask,” she said.

Failing schools, high dropout rates and gang affiliation seem to be high in those areas, Dupnik said.

“Sunnyside is, I think, the area where the problem is most acute,” he said.

Dupnik stressed that he is not encouraging school districts to break the law.

Dupnik’s opinion arose when he attended a hearing on border violence held by the U.S. Senate Homeland Security and Governmental Affairs Committee, he said.

“I just brought up an issue that was not being dealt with that I felt should be dealt with,” Dupnik said at a news conference Tuesday afternoon.

“It’s a subject that nobody wants to talk about,” he said. “I merely aired an idea. I’m not on a platform. I don’t have a plan. I don’t have a strategy.”

Dupnik said he will not conduct immigration sweeps at area schools.

“I find that thought repulsive and repugnant,” he said.

Nor will the Sheriff’s Department stage similar sweeps anywhere in the community, he said.

“We will never do that as long as I am sheriff here.”

The grisly discovery happened days after Roman Catholic Archbishop Hector Gonzalez Martinez created a stir by saying that Sinaloa cartel leader Joaquin “El Chapo” Guzman lives near the town of Guanacevi, in Durango state, and that “everybody knows it except the authorities.”

The bullet-riddled bodies of the two army officers were found in the Durango township of Tepehuanes, about 30 miles (50 kms) south of Guanacevi.

The army said in a statement Wednesday that the two officers were off duty when they were killed, and that it had increased patrols in the area to look for the assailants.

Local news media reported that the bodies were found with a sign that read “neither the government nor priests can handle El Chapo,” an apparent reference to the archbishop’s comments and the government’s posting of a $2.1 million reward for Guzman in March.

An army official, who was not authorized to be quoted by name, and a local official in Tepehuanes, who asked that his name not be used for fear of retaliation, confirmed that a message was found with the bodies. But they could not say what it said.

The location of Guzman, who escaped from prison in 2001, has become a part of Mexican folklore, with rumors circulating of him being everywhere from Guatemala to almost every corner of Mexico, especially its “Golden Triangle,” a mountainous, marijuana-growing region straddling the northern states of Sinaloa, Durango and Chihuahua.

Officials in Guanacevi, a small mining hamlet of about 2,500, said the town “totally rejects” it is home to Guzman.

“If they’re so sure this man is here, why haven’t they presented any evidence?” said Pablo Vargas, secretary of the Guanacevi town council.

Guzman has long been reported to move around frequently, using private aircraft, bulletproof SUVs and even all-terrain vehicles. The heavily forested mountains around Guanacevi have few roads, making it a prime spot as a hideout.

Also Wednesday, the Defense Department announced that soldiers captured Isaac Manuel Godoy Castro, an alleged top member of the Arellano Felix cartel. The department said Godoy Castro led a cell of the cartel and answered directly to its suspected leader, Fernando Sanchez Arellano, known as the “the engineer.”

Godoy was arrested Tuesday, along with six other alleged members of his cell, the department said. They were found with four guns and marijuana.

Adm. Michael Mullen, who spoke to reporters after a brief tour of the border in and around El Paso, Texas, said his first trip to the area should not be taken as a sign of any intentions to send the military to the border as a bloody drug cartel war plagues Mexico.

“There are (no plans) that I am aware of or that I would talk about,” Mullen said. “I’m here to learn more about it (the border), specifically because of my responsibilities, and we’ll continue to support just as we have in the past.”

Mullen said his briefings from commanders with the Army’s Joint Task Force North at nearby Fort Bliss and the U.S. Border Patrol were only designed to ensure continued cooperation among authorities.

As violence continues to mount in Mexico’s battle with warring drug cartels — more than 10,670 people have been killed since Mexican President Felipe Calderon launched a government offensive against the powerful drug gangs in 2006 — governors and members of Congress have increasingly called on President Barack Obama to send troops to the southern frontier.

In February, Texas Gov. Rick Perry asked U.S. Homeland Security Secretary Janet Napolitano for 1,000 troops to augment local efforts along the border.

Last month Arizona Gov. Jan Brewer wrote Defense Secretary Robert Gates asking for 250 National Guard troops to be sent to the Arizona-Mexico border to supplement 150 troops already there as part of a long-standing border assistance program.

Her spokesman, Paul Senseman, said the request was prompted by a combination of Arizona’s problems from immigrant and drug smuggling and Mexico’s war with drug cartels.

Arizona’s senators, John McCain and Jon Kyl, both have urged the deployment of soldiers.

National Guard troops are already at the Arizona border assisting in anti-drug efforts, helping federal agents inspect vehicles at ports of entry.

The situation is similar in New Mexico, where this week National Guard officials also asked for 100 more troops — at a cost of about $5 million — to help with anti-drug missions along the state’s nearly 180-mile border with Mexico.

Capt. Amanda Straub, a New Mexico National Guard spokeswoman, said Friday that Guard officials there don’t want troops to act as law enforcement but just expand a nearly two-decade old anti-drug effort.

As governor, Napolitano in 2006 asked the federal government to pay for sending more troops to the border.

Despite Mullen’s statements Friday, Napolitano said the requests for troops were under consideration.

The reaction to the calls for help from the federal government has been mixed.

During a stop in Nogales, Ariz. Wednesday, Napolitano said the requests were being reviewed.

But hour’s before Napolitano stop in Nogales, her newly appointed “border czar” Alan Bersin said that the posse comitatus act, which limits the ability of military forces, including the National Guard, from performing law enforcement duties inside the United States, has served the country well.

“We should be very cautious to not … misstate the security situation,” Bersin said Wednesday in El Paso shortly after being introduced as Napolitano’s border czar. He noted that there had been no direct spillover of the violence seen in northern Mexico, though cartel-affiliated drug and immigrant traffickers are thought to be responsible for kidnapping and other crimes farther north of the border.

U.S. troops along the border is nothing new. In 2006, then President George W. Bush sent thousands of National Guard troops to the border to help the Border Patrol conduct surveillance and other security operations while that agency bolstered its own ranks.

U.S. Army soldiers from Joint Task Force North, whose commanders briefed Mullen Friday, has also long run anti-drug and other security missions along the Mexican border.

McCain told a crowd at a business luncheon that border violence has reached a point where the government should respond to requests from the governors of Arizona and Texas to station additional Guard troops at the border.

“I don’t envision it for an extended period of time, but right now, we need the Guard on the border because of this violence,” McCain said in response to a question from an Arizona National Guard member.

Govs. Jan Brewer of Arizona and Rick Perry of Texas have asked the federal government to send troops to the border to strengthen security there. Brewer’s office has said her request was prompted by a combination of Arizona’s problems from immigrant and drug smuggling and rising violence in Mexico’s drug war.

Mexico’s government is battling drug cartels at the same time that drug groups are fighting each other for the most lucrative smuggling routes into the United States. More than 10,650 people have been killed in drug violence in Mexico since President Felipe Calderon sent out 45,000 troops in 2006 to directly confront the traffickers.

Although there is disagreement in law enforcement circles about whether Arizona has already experienced spillover violence from Mexico, immigration agents over the years have noted alarming violence in the immigrant smuggling business, and Phoenix has experienced a rash of kidnappings tied to the drug and immigrant smuggling business.

Homeland Security Secretary Janet Napolitano has plans to send nearly 500 federal agents and support personnel to the border.

After speaking at the luncheon held by the Arizona Chamber of Commerce and Industry, Kyl said Guard members did an effective job in the past of assisting federal border authorities and deterring drug and immigrant smuggling operations.

“There is something about the U.S. military that (the smugglers) don’t want to mess with,” Kyl said.

The Bush administration sent thousands of Guard troops to the border to perform support duties so that federal border authorities would be freed up to focus on border security. Bush’s buildup began in 2006 and ended last year.

A much smaller group of Guard troops is already working at certain border points as part of a long-standing program in which National Guard troops assist in anti-drug efforts and help federal agents inspect vehicles at ports of entry.

WASHINGTON – Growing numbers of children of illegal immigrants are being born in this country, and they are nearly twice as likely to live in poverty than those with American-born parents, an independent research group says.

The study released Tuesday by the Pew Hispanic Center highlights a growing dilemma in the immigration debate: Illegal immigrants’ children born in the United States are American citizens, yet they struggle in poverty and uncertainty along with parents who fear deportation, toil largely in low-wage jobs and face layoffs in an ailing economy.

The analysis by Pew, a nonpartisan research organization, estimated that 11.9 million illegal immigrants lived in the U.S. as of March 2008. Of those, 8.3 million, or 5.4 percent of the U.S. labor force, worked primarily in lower-paying farm, construction or janitorial work.

Roughly 3 out of 4 of their children – or 4 million – were born in the U.S. In 2003, 2.7 million children of illegal immigrants, or 63 percent, were born in this country.

“One of the most striking features is that it is a population largely made up of young families,” said Jeffrey Passel, an author of the report. “This is a different picture than we usually see of undocumented immigrants – of young (single) men, the day laborers on street corners.”

Children of illegal immigrants hold a delicate place in the U.S.

On the one hand, the Supreme Court ruled in 1982 that these children – whether they were U.S. citizens or not – were entitled to a public school education. California and a few other states also provide in-state college tuition rates to illegal immigrants.

At the same time, the immigrants and their families are among the poorest people in the U.S., easily exploited by employers and subject to arrest at any time. Children who are U.S. citizens cannot petition for their parents to become legal U.S. residents until they are at least 21.

———

AMONG THE FINDINGS

• One-third of the children of illegal immigrants live in poverty, nearly double the rate for children of U.S.-born parents.

• The 2007 median household income of illegal immigrants was $36,000, compared with $50,000 for U.S.-born residents.

• About 47 percent of illegal immigrant households have children, compared with 21 percent for U.S.-born residents and 35 percent for legal immigrants.

The Associated Press

“On the Mexican side, more uniform and routine collection of arms tracing done on a real-time basis” will be required, Napolitano told The Associated Press as she flew to an arms trafficking conference in Cuernavaca.

Napolitano and U.S. Attorney General Eric Holder met privately with their counterparts, Mexican Attorney General Eduardo Medina-Mora and Interior Minister Fernando Gomez-Mont, as well as other Mexican and U.S. officials to discuss tougher penalties for violating the countries’ gun laws as one way of fighting drug cartels blamed for violence on both sides of the border.

Most of the weapons being used in the Mexican drug wars — 6,290 people died last year and more than 1,000 this year — are smuggled across the border from gun dealers in the United States.

Until recently, the U.S. did not regularly inspect southbound vehicles, and the Mexicans didn’t scan the majority of the cars coming into the country. Facilitating legal trade, not catching gun smugglers, has been the prime directive, Mexican officials have said. Now, the cartel security threat demands a new approach.

The Obama administration has promised a crackdown on illegal U.S. weapons sales that supply the drug cartels.

The Cuernavaca meetings come one day after Napolitano announced plans to spend more than $400 million to upgrade U.S. ports of entry and surveillance technologies to help thwart drugs and arms smuggling along the border.

Napolitano said the U.S. and Mexico are in a better position than ever before to take on this fight.

“Now you have the political will at the highest reaches of the Mexican government to take this on and to be public about it,” she said. “That combined with our own interest in taking on these cartels and the resources that we have give you kind of a one-two punch that we didn’t have at that level before.”

Besides the $400 million, which is part of President Barack Obama’s economic stimulus package approved by Congress, Napolitano has directed her department to step up its outbound inspections. Customs and Border Protection officials would not provide specific details, but said there were about five outbound inspection operations in the past year.

Two weeks ago Customs officials at the eight railroads between the U.S. and Mexico began scanning rail cars on the way out of the U.S. instead of just on their way in. When U.S. officials see something suspicious in the X-ray, they alert Mexican law enforcement, which intercepts the rail cars in Mexico.

It was as simple as flipping a switch, said Marko Lopez Jr., chief of staff for Customs and Border Protection.

Lopez, who came on recently with the new administration, said he did not know why this wasn’t being done before. “Bottom-line is that we weren’t,” Lopez said. “It’s a huge vulnerability.”

Members of an alleged kidnapping gang are shown with their weapons to the media in Tijuana, Mexico, in this Dec. 18 file photo. Mexico insists the U.S. do more to stop a little-publicized form of border smuggling that is arming the world's most powerful drug cartels with U.S. assault rifles. Cartels have killed more than 1,000 people so far this year south of the border.

MEXICO CITY – Try to bring a refrigerator into Mexico in the back of your pickup, and you are almost certain to get stopped by Mexican customs officials.

Stick a couple of AK-47 rifles in your trunk, and chances are you’ll whiz right through.

Now Mexico is owning up to its leaky border as it launches a new program to monitor vehicles entering the country. The goal is to weigh and photograph southbound cars and trucks, in hopes of snaring more gun smugglers.

As the Obama administration promises a crackdown on the illegal U.S. weapons trade that supplies the drug cartels, Mexico is acknowledging shortcomings on its side of the 2,000-mile border.

“Security concerns require a customs overhaul,” Alfredo Gutierrez Ortiz, who oversees border checkpoints as director of Mexico’s tax collection agency, said in an interview Wednesday with The Associated Press. “Today, passenger vehicles really enter without being inspected.”

Mexico checks only 10 percent of the 230,000 vehicles that cross the border each day, according to the federal Attorney General’s Office. By weighing cars to see if they are unusually heavy, and running license plate numbers through a database of suspicious vehicles, the government hopes to catch more hidden contraband.

The United States has long weighed and checked the license plates of northbound vehicles, but the technology is new to Mexico, which is installing it at all customs checkpoints. It was introduced last week at Matamoros, across the Rio Grande from Brownsville, Texas, and should be added along Mexico’s border with Guatemala by year’s end.

Such a systematic effort would be a big improvement: Inspections are now mostly determined by lights that randomly flash red or green. Frequent travelers say it is rarely red.

Inside Mexico, strict gun control laws prohibit sales of weapons with calibers higher than a .38 handgun. Even to buy those, citizens must get permission from the Defense Department.

North of the border, however, the cartels simply pay straw buyers to pick up weapons at gun shops, gun shows or flea markets, then resell the arms to smugglers.

The ATF says it has traced up to 95 percent of guns seized at scenes of drug violence in Mexico to U.S. commercial sources. These weapons are increasingly higher-powered, including .50 caliber Barrett rifles and ammunition that can pierce the armor of Mexican soldiers and police.

“A year ago, we never saw those guns going south into Mexico,” said Tom Mangan, a spokesman for the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives. “Now we refer to it as one of the weapons of choice.”

Mexico’s modernization effort coincides with President Obama’s pledge to dispatch nearly 500 more federal agents to the border, along with X-ray machines and drug-sniffing dogs, both to stop the spillover of Mexico’s drug violence and curb gun smuggling. Homeland Security Secretary Janet Napolitano and Attorney General Eric Holder will be in Mexico Thursday to reinforce the U.S. commitment in talks with their Mexican counterparts.

Experts are skeptical about their chances of slowing the weapons supply. Gun runners easily smuggle thousands of weapons in small numbers at a time, taking them apart and hiding them in suitcases or even inside televisions and DVD players. These weapons wouldn’t necessarily be detected by weight.

“If the car has no criminal record, and is apparently legal, it will not necessarily be stopped and checked,” said Georgina Sanchez, a gun trafficking expert with the Mexican think-tank Collective for the Analysis of Security and Democracy.

Smugglers also can avoid checkpoints entirely, carrying weapons south along the same desolate corridors that bring drugs and migrants north.

And while cartels get most of their high-caliber assault rifles from the U.S., they are turning to Central America for other military-grade weaponry such as grenades and even the occasional rocket launcher.

“You’re seeing truly military-type guns, like grenade launchers,” Mangan said. “They’re not coming from the U.S. The hand grenades that are being used, you’re looking at that stuff migrating up from Central America.”

Experts also agree that the Mexican military, which is often outgunned by traffickers, has not been a significant source of weapons despite the potential for corrupt soldiers to sell out to the cartels.

Many of the cartels’ grenades and other heavy weapons could be leftovers from Central America’s civil wars, Mangan said.

Mexico has seized more than 2,702 unexploded grenades since the start of President Felipe Calderon’s term in December 2006, compared to 59 during the first two years of the previous administration. Grenades have been traced back to the militaries of many countries, from South Korea to Spain and Israel, Mangan said.

Gutierrez acknowledged that the new system will not be as effective on the southern border, where many communities straddle the frontier and residents regularly bypass official crossings.

“We need to address the breach – everything that doesn’t go through customs – because that’s the biggest problem in the southern border,” he said.