Manssor Arbabsiar is shown in this 2001 Nueces County, Texas, Sheriff's Office photograph released to Reuters on October 11, 2011.
The U.S. has charged two men in what they claim is an Iranian-backed plot to assassinate a Saudi ambassador.
U.S. Attorney General Eric Holder said Iran "conceived, sponsored and directed" a plot to kill Saudi ambassador Adel Al-Jubeir by bombing one of his favourite restaurants.
The two accused were named as Manssor Arbabsiar, a 56-year-old naturalized U.S. citizen with an Iranian passport, and Ali Gholam Shakuri, who is said to be a member of Iran's elite Quds Force, a unit of the Revolutionary Guard. Manssor was arrested at New York's Kennedy Airport on Steptember 29 and appeared in court Tuesday. Shakuri remains at large and is reportedly in Iran.
Arbabsiar sought help carrying out the killing and unknowingly enlisted the help of an undercover Drug Enforcement Administration informant who was posing as a member of Mexico's Zetas drug cartel. The informant demanded $1.5 million for the killing and Arbabsiar had allegedly wired $100,000 to a U.S. bank account as a down payment.
According to a statement from the U.S. Justice Department, the undercover agent warned Arbabsiar that the restaurant bombing would likely kill multiple senators and other civilians, but Arbabsiar dismissed the possible bloodbath as "no big deal."
U.S. Secretary of State Hillary Clinton said the U.S. "will be consulting with our friends and partners around the world about how we can send a very strong message that this kind of action, which violates international norms."
Iran's parliament speaker Ali Larijani called the U.S. reports a "childish game."