(CNN) -- An Argentine special prosecutor's accusation that Iran has established terrorist networks throughout Latin America has renewed debate over how big a threat that poses to the region and the United States.
Alberto Nisman, who is investigating the 1994 bombing of a Jewish community center in Buenos Aires that killed 85 people, said in a 500-page report released last week that Iran has been building the networks for nearly 30 years.
That assessment coincides with a viewpoint held by many Western analysts.
"As Nisman points out, the Iranians have been actively setting up intelligence and operational structures in Latin America since the 1980s," said Douglas Farah, a senior fellow at the International Assessment and Strategy Center.
And that infiltration has progressed since, Farah notes.
Nisman's report said Iran's intelligence activities in Latin America are being conducted directly by Iranian officials or through a key surrogate, the Hezbollah Islamic militant group. "Criminal plans" by Iran could be under way in Brazil, Colombia, Chile, Paraguay, Uruguay Suriname and Trinidad and Tobago, the report said.
"They are more involved in the cocaine trade than ever before, and have greater access in the region due their allies in Venezuela, Ecuador, Bolivia and elsewhere," Farah said. "So they have more freedom of movement and fewer restrictions. This has greatly increased their capacity to carry out intelligence operations, train and position operatives and prepare attacks, particularly if Israel or the U.S. strikes Iran's nuclear facilities."
But analysts and observers disagree over Iran and Hezbollah's ambitions. Hezbollah's actions are mainly seen as financial, as evidenced by greater ties to Latin American drug cartels in recent years. At the same time, Iran may be returning to more violent acts, such as a reported attempt to recruit someone to assassinate a diplomat.
"Hezbollah's presence in Latin America is growing and the organization remains the premiere terrorist organization in the world," Farah testified to a House subcommittee in July 2011. "It is growing both in economic capacity and in its placing of operatives in the region through the rapid expansion of Iran's diplomatic and intelligence missions, businesses and investments."
Iran has denied any connection to the July 18, 1994, bombing at the Argentine Jewish Mutual Association (known as AMIA after its Spanish acronym), which also injured more than 100 people. Likewise, Iran denies any involvement in a bomb blast at the Israeli Embassy in Buenos Aires on March 17, 1992, that killed 29 people and wounded at least 250 more.
Iran and Argentina signed an accord in January to appoint a joint special commission to investigate the 1994 attack.
Roger Noriega, a former U.S. ambassador to the Organization of American States, testified before Congress in March that Iran has more than 80 operatives in at least 12 Latin American nations.
Hezbollah, a Lebanese Shiite political and paramilitary group labeled a terrorist organization by the United States and several other Western nations, is widely seen by Western governments as Iran's conduit to Latin America.
"It is said that wherever Iran goes, Hezbollah is not far behind," Noriega told Congress.
Analysts agree that Hezbollah started its infiltration of Latin America in the mid-1980s, establishing its first major stronghold in the Tri-Border Area, a relatively lawless region along the frontiers of Argentina, Brazil and Paraguay. From this base deep in the heart of South America, Hezbollah set up illicit enterprises to fund its operations in the Middle East and elsewhere, analysts say. Among the organization's reported major undertakings are money-laundering, counterfeiting, piracy and drug trafficking.
By all accounts, those illegal activities are quite lucrative. A 2004 study for the Naval War College determined that Hezbollah's operations in the Tri-Border Area generated about $10 million annually. A 2009 Rand Corporation report said Hezbollah netted around $20 million a year in the area. As a result, says Rachel Ehrenfeld, author of the book "Funding Evil," the Tri-Border Area constitutes Hezbollah's most significant source of independent funding.
Hezbollah started to become more involved in Latin America and western Africa in 2006, when the group had "significant fallout" with Iran over funding, Farah said.
"They didn't like Iran telling them what to do with their money," he said.
So Hezbollah looked for other ways to raise revenue. U.S. officials have estimated that Iran had been giving Hezbollah anywhere from $60 million to $100 million a year, and maybe even up to $200 million.
But it's not all about money. Hezbollah also uses its new stronghold as a base for recruiting among Latin America's diaspora of Lebanese expatriates, known throughout the region as 'turcos," and other Muslim populations.
Much of that recruitment takes place in mosques or "Islamic centers" that Hezbollah operatives infiltrate or establish to serve the region's burgeoning Muslim communities.
Although exact figures are difficult to come by, estimates by the Pew Research Center and the Islamic Population websites say Brazil and Argentina have the largest Muslim populations in South America, with more than 1 million members each. Those populations include converts to Islam, Arab immigrants and their descendants. Venezuela has more than 100,000 Muslims concentrated among persons of Lebanese and Syrian descent, according to the U.S. State Department's 2008 International Religious Freedom Report.
It wasn't long after Hezbollah established its firm foothold in the Tri-Border Area that it became linked to the two terrorist attacks in Argentina, which has the largest Jewish community in South America and one of the biggest outside of Israel.
By September 1995, Philip Wilcox Jr., the State Department coordinator for counterterrorism, was testifying to a U.S. House committee that Hezbollah had become "the major international terrorist threat" in the region.
Although widely blamed for the attacks, Hezbollah denied any involvement, and there has been a strongly held belief through the years that high-level Iranian officials were more directly involved.
Despite the deadly attacks in Argentina, many analysts believe Hezbollah's main intent in Latin America centers more on fundraising and recruitment than acts of violence.
The organization has become more involved in the drug trade with the Revolutionary Armed Forces of Colombia, a Marxist rebel group commonly known as the FARC. The rebels use the profits from narcotrafficking to buy weapons and other necessities to fund their 47-year-old insurrection.
"There's no question they have become much more intertwined in the drug trade, primarily through the FARC, but not exclusively," Farah said. "But I have not seen them involved in military activities in any visible way."
Security analyst Samuel Logan, the founding director of Southern Pulse, an online information network focused on Latin America, sees the same dynamic at work.
"They're involved in raising money for their operations in the Middle East," he told CNN.
Melani Cammett, a political science professor at Brown University, took an even stronger stance in testimony before a U.S. House subcommittee in July 2011.
"Latin America is home to many Lebanese Shia migrants, but they have diverse religious and political orientations," Cammett testified. "Sympathy for Hezbollah as the leader of Resistance, as well as the paying of religious taxes to Shia clerics, even those linked to Hezbollah, are not commensurate to support for or participation in terrorist acts."
That's not to say, though, that Hezbollah does not have the capacity to turn violent, particularly at the behest of Iran.
Ilan Berman, vice president of the American Foreign Policy Council, said Hezbollah "represents a significant potential threat to the United States."
"Over the past decade, Hezbollah's regional activities have shown a clear pattern of targeting U.S. interests and assets throughout Latin America. Among other indicators, Hezbollah operatives are known to have cased the U.S. embassy in Paraguay's capital of Ascunción, and local organizational cells have colluded with al Qaeda to plot attacks on U.S. and Jewish targets in the region," he said.
"Hezbollah also has the ability to strike at the U.S. homeland itself," Berman said. "Given the lucrative nature of the organization's illicit activities throughout the hemisphere, the likelihood of such a development remains low. Still, Hezbollah's strategic calculus could conceivably change if it or its chief sponsor, Iran, were imperiled in a substantial way (for example, through military action that targets Iran's nuclear facilities). In this sense, Hezbollah can be described as a potential insurance policy of sorts for the Iranian regime."
And Hezbollah only stands to become more dangerous, analysts say.
For example, authorities have uncovered several recent instances of Hezbollah involvement with criminal elements to obtain funding.
One of the most significant was Operation Titan, a 2008 bust by U.S. and Colombian authorities of an international cocaine-smuggling and money-laundering ring that funneled part of its profits to Hezbollah.
That same year, the U.S. Treasury Department's Office of Foreign Assets Control identified two Venezuela-based supporters of Hezbollah, one of them being senior diplomat Ghazi Nasr al Din. Authorities said he was a significant Hezbollah fundraiser. The other man, Fawzi Kan'an, was accused of using his two Venezuela-based travel agencies to funnel money to Hezbollah.
In 2010, U.S. authorities accused Lebanese native Ayman Joumaa of selling Colombian cocaine to the Mexican Zetas drug cartel and laundering money for the drug-trafficking organization and channeling the profits to Hezbollah.
The Zetas, one of Mexico's most ruthless cartels, also was in the news in October 2011, when U.S. officials said Iranian operatives tried to recruit cartel members to assassinate a Saudi diplomat in Washington.
That's a step too far, some high-level U.S. officials say.
Iran's purported action "shows that some Iranian officials — probably including Supreme Leader Ali Khamenei — have changed their calculus and are now more willing to conduct an attack in the United States in response to real or perceived U.S. actions that threaten the regime," Director of National Intelligence James Clapper testified to Congress in January 2012.
Hezbollah has gained entry into Latin America through Iran, which has strengthened ties with Venezuela, Bolivia, Ecuador and Nicaragua. That is particularly worrisome to some longtime Latin America watchers, including Noriega, the former U.S. ambassador to the Organization of American States.
"In addition to operational terrorist activity, Hezbollah also is immersed in criminal activity throughout the region -- from trafficking in weapons, drugs, and person," he testified in March. "If our government and responsible partners in Latin America fail to act, I believe there will be an attack on U.S. personnel, installations or interests in the Americas," Noriega said.
Other analysts say the U.S. is safe -- for now, at least.
"The U.S. policy community generally believes Iran and Hezbollah do not pose a significant threat, at least in the short term," Farah told CNN last week.
"(T)he proposition that Hezbollah intends to launch terrorist acts against the U.S. from the region are not based on conclusive evidence," said Cammett, the professor at Brown.
Berman, the vice president at the American Foreign Policy Council, also has come to the same conclusion.
"Hezbollah's presence in the Western Hemisphere is manifested in 'support' activities: those that provide financial, operational or political benefit to the organization at large, and to its principal sponsor, the Islamic Republic of Iran," Berman told a Congressional hearing. "As a result, absent a significant precipitating development in the Middle East, the likelihood of a terrorist attack on the United States by Hezbollah in the near future remains low."