In announcing details of the alleged Iranian plot to carry out a spate of terrorist attacks in Washington, including murdering the Saudi Arabian ambassador, U.S. Attorney General Eric Holder left little room for doubt.The plot was "directed and approved by elements of the Iranian government and, specifically, senior members of the Quds Force," Holder said, referring to the elite unit widely believed to be in charge of the Islamic Revolutionary Guards Corps' (IRGC) activities abroad. "High-up officials in those agencies, which is an integral part of the Iranian government, were responsible for this plot," the attorney general went on.Thus did Washington imply that the very highest echelons of Iran's Islamic regime conspired to carry out a murder on U.S. soil that would have plunged the Persian Gulf and the wider Middle East into turmoil, if not all-out war.But why would the leadership in Tehran -- renowned, despite its fierce rhetoric, for acting with calculated caution -- behave in what some analysts have said is a reckless fashion?Ali Ansari, head of Iranian studies at St. Andrews University in Scotland, declares himself an "agnostic" on the affair. The hoopla accompanying it fails to conceal the fact that this is not a "Cuban missile-crisis moment," where accusations are backed up with firm evidence, he says."I'm agnostic because it's not credible as far as previous Iranian activities are concerned and the charges are so serious, and the consequences would be so severe that it behooves us to be really very sober in looking at these allegations and seeing what evidence there is," Ansari says."At the moment it looks as if there is one individual who has obviously been in communication with an undercover FBI agent who has obviously made a number of very serious assertions and allegations and some money has crossed hands; but I would like to see a little bit more detail before I'm convinced," he adds. "There's also a problem about believing what this chap has said. We have no idea who this guy is."Indeed, Mansur Arbabsiar, the 56-year-old Iranian-American from Corpus Christi, Texas, who has been arrested as a central figure in the alleged conspiracy, seems an obscure and unlikely figure. Said to have been recruited by his cousin, a Quds officer in Iran, he is described as a used-car salesman. This mundane occupation belied his involvement in an intricate plot under which, according to U.S. officials, he would pay $1.5 million to the Los Zetas drug cartel to kill the Saudi ambassador at a Washington restaurant also frequented by congressmen and senators.The plotters also planned to attack the Israeli Embassy in Washington and the Saudi and Israeli diplomatic missions in Argentina, according to the indictment.Unknown to Arbabsiar, the co-conspirator he thought was from Los Zetas was an informer for the U.S. Drug Enforcement Agency.With that background of banality and operational incompetence, there are justified reservations about his authenticity, Ansari suggests."This just requires a little bit of standing back, looking at the facts soberly, and seeing what the Americans have," Ansari says. "At the moment it seems that there's an individual who we have no real background about -- we don't know if he's a bit of a Walter Mitty character, for instance, whether he's got himself involved in something that frankly is out of his depth. But he has been conversing with this undercover agent whom he obviously didn't know was an undercover agent, and that's really the basis of the evidence as far as I can see for the time being."Robert Baer, a former CIA agent and longtime observer of the Quds Force, was more blunt,newspaper: "This stinks to holy hell. The Quds Force are very good. They don't sit down with people they don't know and make a plot. They use proxies and they are professional about it. If [Quds Force head] Kassim Suleimani was coming after you or me, we would be dead. This is totally uncharacteristic of them."U.S. preoccupation with the Quds Force is well established. U.S. officials have long blamed the organization as the architect of instability and anti-American insurgency in Iraq and Afghanistan.Iran has a history of conducting assassinations of its political enemies abroad. Shapur Bakhtiar, prime minister when the regime of the last shah was toppled in 1979, was murdered in 1991 while exiled in France. The following year, four Iranian-Kurdish opposition leaders were assassinated in a restaurant in Berlin. While an Iranian and a Lebanese were convicted of the murders, an international arrest warrant was later issued for the then-Iranian intelligence minister, Ali Fallahian, after a court ruled that he had ordered the assassinations.Attacks carried out in Argentina also have a precedent. Several senior Iranian officials, including Fallahian, have also been implicated by Argentinean judges for a 1994 bomb attack on a Jewish community center in the Argentinean capital, Buenos Aires, which killed 85 people. Iran was also suspected of having a hand in the 1992 bombing of Israel's embassy in Buenos Aires, in which 29 people were killed. Responsibility for the attack was claimed by the Islamic Jihad organization, said to have links to Iran.Hostility between Iran and Saudi Arabia is well-known. Relations between the two Persian Gulf neighbors have been described as being in a state of "cold war." The enmity was summed up in a comment attributed to Saudi King Abdullah in the diplomatic cables leaked by WikiLeaks, in which he urged the United States to "cut off the head of the snake" and attack Iran.Yet the obvious question, many believe, concerns the idea of attacks on U.S. soil. Ansari considers such a move highly unlikely. "If they wanted to do certain things, they would do them in the region. I think there was one occasion, right in the early days of the revolution, where they assassinated a former member of the Iranian Foreign Ministry in the Washington area," he says."But it's very, very rare for them to be contemplating this sort of operation, particularly against a foreign national and on American soil. If you had said it was in Europe, there's certainly a possibility, there is a track record there."