WASHINGTON - Iran Air 744 is a bimonthly flight that originates in Tehran and flies directly to Caracas with periodic stops in Beirut and Damascus. The maiden flight was Feb. 2, 2007.

The mere existence of the flight was a significant concern for U.S. intelligence officials, but now a broader concern is who and what are aboard the flights.

"If you [a member of the public] tried to book yourself a seat on this flight and it doesn't matter whether it's a week before, a month before, six months before -- you'll never find a place to sit there," says Offer Baruch, a former Israeli Shin Bet agent.

Baruch, now vice president of operations for International Shield, a security firm in Texas, says the plane is reserved for Iranian agents, including "Hezbollah, the Revolutionary Guard (IRGC) and other intelligence personnel."

Current and former U.S. intelligence official fear the flight is a shadowy way to move people and weapons to locations in Latin America that can be used as staging points for retaliatory attacks against the U.S. or its interests in the event Iranian nuclear sites are struck by U.S. or Israeli military forces.

"My understanding is that this flight not only goes from Caracas to Damascus to Tehran perhaps twice a month, but it also occasionally makes stops in Lebanon as well, and the passengers on that flight are not processed through normal Venezuelan immigrations or customs. They are processed separately when they come into the country," says Peter Brookes, senior fellow for National Security Affairs at the Heritage Foundation.

The 16-hour flight typically leaves Tehran and stops at Damascus International Airport (DAM), which is Syria's busiest. In 2009, almost 4.5 million passengers used the airport.

After a 90-minute layover, the flight continues the remaining 14 hours to Venezuela's Caracas Maiquetía International Airport (CCS). Upon arrival, the plane is met by special Venezuelan forces and sequestered from other arrivals.

"It says that something secretive or clandestine is going on that they don't want the international community to know about," says Brookes, a former deputy assistant defense secretary for Asian and Pacific Affairs and CIA employee.

"The fact that there is a flight is of course of interest, but the fact that not anybody can gain access to this flight or buy a ticket for that flight is of particular curiosity and should be of concern to the United States."

In addition to speculation about who is aboard, there are significant concerns that the Boeing 747SP airplane might be transporting uranium to Tehran on the return flight. The U.S. government has enacted strong sanctions against Iran because of its nuclear program and there are worries the flight might provide an opportunity to skirt the embargo against materials that might be used for the program.

"Clearly, Iran has been a sponsor of Hezbollah, and clearly Hezbollah profits from this relationship," former CIA Director Michael J. Hayden says.

"It would be too much to say that Hezbollah is a puppet of the Iranian state, but one way of looking at this relationship is that the Iranian state might rely on Hezbollah as a strategic weapon -- its weapon for global reach."

Hayden, now a principle in the Chertoff Group, says the CIA has been aware of the activities for several years.

"Fundamentally, the thing that first and very solidly caught our attention at the Agency was the inauguration of direct air flight between the two capitals. Here was a conduit that people could travel from Iran into the Western Hemisphere, into Latin America in a way that would be very difficult for American intelligence services to detect and to understand.

"Right there at that very simple level, just the direct flight is something that we would be and should be concerned about."

Brookes says the passengers "may not even need visas because they are special passengers. That obviously is of concern because there is no transparency about who the people are coming in and going out of the country. Of course there is concern that these folks may be Iranian special agents."

Beyond concerns about Iranian intelligence flooding the west, Brookes and others worry that Iranian special advisers are schooling the Venezuelan military and may be involved in plans to move Iranian agents inside the U.S.

"It's certainly a possibility. Would the agents that come into Venezuela be able to find their way to the United States? That's certainly possible. You see the drug smugglers today using submersibles to move drugs to the U.S. and other parts of the Caribbean which is a real challenge. So why wouldn't they be able to do the same with persons?"

A U.S. official who spoke on the condition of anonymity says there are concerns about the relationships between Iran and Venezuela, but you have to keep it in perspective.

"The problems both countries face internally, and their own regional priorities closer to home, limit the amount of trouble they can cause together. But it's something you have to watch, whether it's the potential for government-to-government mischief or the possibility of something involving Iran's friends like Hezbollah.

"You can ask what a self-proclaimed Bolivarian socialist has in common with a bunch of theocratic thugs in Iran. The answer is 'not much,' beyond a taste for repression and a shared desire to make life difficult for the United States and its allies."

On Friday, the next flight is expected to take off. While U.S. intelligence may be able to track the flight, there appears to be little more they can legally do to determine what or who is on board.

"American intelligence services have a lot of things on their plate. The fact that I can tell you that we're really interested in that direct flight tells you that it was on our scope -- something that we are sensitive to," Hayden says. "Are we doing enough about it? I would have to say 'no,' because it's a very challenging menu that American intelligence has to deal with."

In a statement, the State Department says, "Nations have the right to enter into cooperative relationships with other nations."

Neither the Iranian nor the Venezuelan governments responded to request for reaction before this article was published.

The Southern border of the U.S and the Ho Chi Minh trail through Laos to Vietnam. Swarms of socialists heading for a weak republic with the goal of destroying it. I'm starting to have big-time flashbacks. At least we were allowed to kill the enemy in Laos. How many of those "illegal aliens" coming through the border are terrorists?

Do a google search for illegal alien OTM and see what you find. The OTM is an acronym for other-than-Mexican, and includes every nationality you can think of, most of which are virulently anti-American and have the desire (and maybe the means) to cause massive destruction at any time in any particular place they choose. If the Israelis (or we?) hit Iran this week while we can, I'd stay away from big cities for a few days.