Two men, including a U.S. citizen, allegedly worked for "factions of the Iranian government" to plot to assassination of the Saudi ambassador and attack the Saudi and Israeli embassies.

Charges have been filed against Manssor Arbabsiar, a 56-year-old naturalized U.S. citizen holding both Iranian and U.S. passports, and Gholam Shakuri, an Iran-based member of Iran's Qods Force, a special operations unit of the Iranian Islamic Revolutionary Guard Corps (IRGC) that is said to sponsor and promote terrorist activities abroad.

Both defendants are charged with conspiracy to murder a foreign official; conspiracy to engage in foreign travel and use of interstate and foreign commerce facilities in the commission of murder-for-hire; conspiracy to use a weapon of mass destruction (explosives); and conspiracy to commit an act of international terrorism transcending national boundaries. Arbabsiar is further charged with an additional count of foreign travel and use of interstate and foreign commerce facilities in the commission of murder-for-hire, the FBI announced in a press release.

While Arbabsiar was arrested on Sept. 29 at John F. Kennedy International Airport, Shakuri remains at large.

"The investigation leading to today's charges illustrates both the challenges and complexities of the international threat environment, and our increased ability today to bring together the intelligence and law enforcement resources necessary to better identify and disrupt those threats, regardless of their origin," said FBI Director Robert Mueller.

Arbabsiar and his Iran-based co-conspirators, including Shakuri of the Qods Force, have allegedly been plotting the murder of Saudi Ambassador Adel al-Jubeir. In furtherance of this conspiracy, Arbabsiar allegedly met on a number of occasions in Mexico with an undercover agent with the Drug Enforcement Administration who posed as a drug-cartel associate. With Shakuri's approval, Arbabsia allegedly wired about $100,000 into a U.S. bank account as a down payment for the assassination, which was to take place in the U.S.

The IRCG is an arm of the Iranian military that's composed of several branches, including the Qods Force. The Qods Force conducts sensitive covert operations abroad, including terrorist attacks, assassinations and kidnappings, and is believed to sponsor attacks against Coalition Forces in Iraq. The Qods Force provides material support to the Taliban and other terrorist organizations.

Arbabsiar met with the operative in Mexico on May 24, where Arbabsiar and explained that he was interested in, among other things, attacking an embassy of Saudi Arabia potentially with C-4 explosives. In June and July, Arbabsiar returned to Mexico and held additional meetings the agent, where he explained that his associates in Iran had discussed several violent missions.

During a July 14 meeting in Mexico, the operative allegedly told Arbabsiar that he would need to use four men to carry out the ambassador's murder and that his price for carrying out the murder was $1.5 million. Arbabsiar allegedly agreed and stated that the murder of the ambassador should be handled first, before the execution of other attacks.

Arbabsiar indicated that his cousin was a "big general" in the Iranian military, focuses on matters outside Iran. and that he had taken certain unspecified actions related to a bombing in Iraq.

During a July 17 meeting in Mexico, the operative noted to Arbabsiar that one of his workers had already traveled to Washington, D.C., to begin surveillance of the ambassador. The complaint alleges that Arbabsiar made it clear that the assassination needed to go forward, despite mass casualties, telling the operative, "They want that guy [the ambassador] done [killed], if the hundred go with him f**k 'em." The agent and Arbabsiar allegedly discussed bombing a restaurant in the U.S. that the ambassador frequented. When the agent noted that others could be killed in the attack, including U.S. senators who dine at the restaurant, Arbabsiar allegedly dismissed these concerns as "no big deal."

On Sept. 28, Arbabsiar flew to Mexico to guarantee final payment. He was refused entry into Mexico and placed on a return flight to the U.S. On Sept. 29, Arbabsiar was arrested by federal agents during a flight layover at JFK International Airport in New York. Several hours after his arrest, Arbabsiar was advised of his Miranda rights; he agreed to waive those rights and speak with law enforcement agents. During a series of Mirandized interviews, Arbabsiar allegedly confessed to his participation in the murder plot and the involvement of the Iranian co-conspirators.

Earlier this month, Arbabsiar made phone calls at the direction of law enforcement to Shakuri in Iran that were monitored. During these phone calls, Shakuri allegedly confirmed that Arbabsiar should move forward with the plot to murder the ambassador and that he should accomplish the task as quickly as possible, stating on Oct. 5, "Just do it quickly, it's late."