Hezbollah is using the same southern narcotics routes that Mexican drug kingpins do to smuggle drugs and people into the United States, reaping money to finance its operations and threatening U.S. national security, current and former U.S. law enforcement, defense and counterterrorism officials say.

The Iran-backed Lebanese group has long been involved in narcotics and human trafficking in South America's tri-border region of Paraguay, Argentina and Brazil. Increasingly, however, it is relying on Mexican narcotics syndicates that control access to transit routes into the U.S.

Hezbollah relies on "the same criminal weapons smugglers, document traffickers and transportation experts as the drug cartels," said Michael Braun, who just retired as assistant administrator and chief of operations at the U.S. Drug Enforcement Administration (DEA).

"They work together," said Mr. Braun. "They rely on the same shadow facilitators. One way or another, they are all connected.

"They'll leverage those relationships to their benefit, to smuggle contraband and humans into the U.S.; in fact, they already are [smuggling]."

His comments were confirmed by six U.S. officials, including law enforcement, defense and counterterrorism specialists. They spoke on the condition that they not be named because of the sensitivity of the topic.

While Hezbollah appears to view the U.S. primarily as a source of cash - and there have been no confirmed Hezbollah attacks within the U.S. - the group's growing ties with Mexican drug cartels are particularly worrisome at a time when a war against and among Mexican narco-traffickers has killed 7,000 people in the past year and is destabilizing Mexico along the U.S. border.

Secretary of State Hillary Rodham Clinton was in Mexico on Thursday to discuss U.S. aid. Other U.S. Cabinet officials and President Obama are slated to visit in the coming weeks.

Hezbollah is based in Lebanon. Since its inception after the Israeli invasion of Lebanon in 1982, it has grown into a major political, military and social welfare organization serving Lebanon's large Shi'ite Muslim community.

In 2006, it fought a 34-day war against Israel, which remains its primary adversary. To finance its operations, it relies in part on funding from a large Lebanese Shi'ite Muslim diaspora that stretches from the Middle East to Africa and Latin America. Some of the funding comes from criminal enterprises.

Although there have been no confirmed cases of Hezbollah moving terrorists across the Mexico border to carry out attacks in the United States, Hezbollah members and supporters have entered the country this way.

Last year, Salim Boughader Mucharrafille was sentenced to 60 years in prison by Mexican authorities on charges of organized crime and immigrant smuggling. Mucharrafille, a Mexican of Lebanese descent, owned a cafe in the city of Tijuana, across the border from San Diego. He was arrested in 2002 for smuggling 200 people, said to include Hezbollah supporters, into the U.S.

In 2001, Mahmoud Youssef Kourani crossed the border from Mexico in a car and traveled to Dearborn, Mich. Kourani was later charged with and convicted of providing "material support and resources ... to Hezbollah," according to a 2003 indictment.

A U.S. official with knowledge of U.S. law enforcement operations in Latin America said, "we noted the same trends as Mr. Braun" and that Hezbollah has used Mexican transit routes to smuggle contraband and people into the U.S.

Two U.S. law enforcement officers, familiar with counterterrorism operations in the U.S. and Latin America, said that "it was no surprise" that Hezbollah members have entered the U.S. border through drug cartel transit routes.

"The Mexican cartels have no loyalty to anyone," one of the officials told The Washington Times. "They will willingly or unknowingly aid other nefarious groups into the U.S. through the routes they control. It has already happened. That's why the border is such a serious national security issue."

One U.S. counterterrorism official said that while "there's reason to believe that [Hezbollah members] have looked at the southern border to enter the U.S. ... to date their success has been extremely limited."

However, another U.S. counterterrorism official confirmed that the U.S. is watching closely the links between Hezbollah and drug cartels and said it is "not a good picture."

A senior U.S. defense official, who spoke on the condition of anonymity because of ongoing operations in Latin America, warned that al Qaeda also could use trafficking routes to infiltrate operatives into the U.S.

"If I have the money to do it - I want to get somebody across the border - that's a way to do it," the defense official said. "Especially foot soldiers. Somebody who's willing to come and blow themselves up. That's sort of hard to do that kind of recruiting, training and development in Kansas City."

Adm. James G. Stavridis, commander of U.S. Southern Command and the nominee to head NATO troops as Supreme Allied Commander-Europe, testified before the House Armed Services Committee last week that the nexus between illicit drug trafficking - "including routes, profits, and corruptive influence" and "Islamic radical terrorism" is a growing threat to the U.S.

He noted that in August, "U.S. Southern Command supported a Drug Enforcement Administration operation, in coordination with host countries, which targeted a Hezbollah-connected drug trafficking organization in the Tri-Border Area."

In October, another interagency operation led to the arrests of several dozen people in Colombia associated with a Hezbollah-connected drug trafficking and a money-laundering ring. Hezbollah uses these operations to generate millions of dollars to finance Hezbollah operations in Lebanon and other areas of the world, he said.

"Identifying, monitoring and dismantling the financial, logistical, and communication linkages between illicit trafficking groups and terrorist sponsors are critical to not only ensuring early indications and warnings of potential terrorist attacks directed at the United States and our partners, but also in generating a global appreciation and acceptance of this tremendous threat to security," he said.

Mr. Braun, who spent 33 years with the DEA and still works with the organization as a consultant, said that members of the elite Quds, or Jerusalem, force of Iran's Revolutionary Guards also are showing up in Latin America.

"Quite frankly, I'm not opposed to the belief that they could be commanding and controlling Hezbollah's criminal enterprises from there," Mr. Braun said.

The DEA thinks that 60 percent of terrorist organizations have some ties with the illegal narcotics trade, said agency spokesman Garrison Courtney.

South American drug cartels were forced into developing stronger alliances with Mexican syndicates when the U.S. closed off access from the Caribbean 15 years ago, Mr. Braun said.

Mexico's transit routes now account for more than 90 percent of the cocaine entering the U.S., he said. The emphasis on Mexico intensified after the Sept. 11 attacks, when beefed-up U.S. security measures greatly reduced access to the U.S. by air and water, he said.

The shift put Mexico's drug cartels in the lead and helped them amass billions of dollars and an estimated 100,000 foot soldiers, according to U.S. defense officials.

Hezbollah shifted its trade routes along with the drug cartels, using Lebanese Shi'ite expatriates to negotiate contracts with Mexican crime bosses, Mr. Braun said.

The World Trade Bridge between Nuevo Laredo and its sister city, Laredo, as well as Interstate 35 and Highways 59, 359 and 83, are like veins feeding the Mexican syndicates, running from southern Texas to cities across the U.S. and as far north as Canada, U.S. officials say. In addition, access routes from El Paso, Texas, to San Diego are also high-value entry points.

Ben Conery contributed to this report.