The White House, State Department, and Treasury Department are all involved in developing new measures against the Iranian government that are to be announced "within hours," in response to a Iranian government-linked plot to assassinate the Saudi ambassador to the United States.

Attorney General Eric Holder led a press conference on Tuesday to unveil the allegations against an Iranian-American and a member of Iran's Quds force, a unit of the Islamic Revolutionary Guards Corps, regarding an elaborate plot to work with Mexican drug cartels to assassinate Saudi Ambassador Adel bin Ahmed Al-Jubeir by bombing a restaurant in Washington. The bombing was alleged to be the first of a host of violent attacks inside the United States.

"The complaint alleges that this conspiracy was conceived, was sponsored and was directed from Iran and constitutes a flagrant violation of U.S. and international law, including a convention that explicitly protects diplomats from being harmed," Holder said. "The United States is committed to holding Iran responsible for its actions."

Calling it an "international murder for hire scheme," that was  "directed by factions of the Iranian government," Holder took reporters through a sting operation that began in May when Iranian-American Manssor Arbabsiar, a 56-year-old naturalized U.S. citizen, contacted an informant working on behalf of the Drug Enforcement Agency with a plan to kidnap the ambassador.

In subsequent discussions with the undercover agent, Arbabsiar updated the plot to include the assassination of the ambassador as the first of what U.S. Attorney for the Southern District of New York Preet Bharara described as " a series of lethal attacks cooked up by the defendants and their cohorts in Iran."

Arbabsiar was allegedly working with his cousin, Gholam Shakuri, a member of the Quds force, and other Iranian agents. According to the complaint, filed today in the Southern District of New York, Shakuri aided Arbabsiar in sending $100,000 to a U.S. bank account as a down payment for the assassination.

Arbasiar and Shakuri were charged on Tuesday 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 also charged with an additional count of foreign travel and use of interstate and foreign commerce facilities in the commission of murder-for-hire.

Arbabsiar was arrested in New York on Sept. 29 after he was denied entry into Mexico. He had been in Iran finalizing details of the plot. Holder said the Mexican government had aided in the months-long investigation. He also said that Arbabsiar had confessed in custody and was cooperating with investigators.

"This case illustrates that we live in a world where borders and boundaries are increasingly irrelevant," said FBI Director Robert Mueller. "Though it reads like the pages of a Hollywood script, the impact would have been very real and many lives would have been lost."

"President Obama was first briefed on this issue in June and directed the administration to provide all necessary support to this investigation," Tommy Vietor, National Security Council spokesman, said in a statement.

"The disruption of this plot is a significant achievement by our intelligence and law enforcement agencies, and the president is enormously grateful for their exceptional work in this instance and countless others."