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.