Washington says Iran ordered an assassination attempt on the Saudi ambassador on American soil, but Iran has hit back with charges that the US has fabricated a plot with Tehran in the role of villain in an attempt to score political points.

US officials are in the process of "uniting world opinion" against Iran. "It's critically important that we unite the world in the isolation of and dealing with the Iranians," United States Vice President Joe Biden said on Wednesday morning.Iran has to be held accountable for that "outrageous act," Biden stated. Biden also said that America’s action against Iran could go beyond sanctions, but added that "we're not going there yet." Officials in Washington are speaking about the need to isolate Iran from the international community.Secretary of State Hillary Clinton stated that Iran poses a threat to the world at large."What everybody is learning is that nobody is safe from the Iranians,” she said. “They have their own logic, their own way of thinking about the world and their place in it and they're vying with everybody for influence."“Let’s hope the United States government is not trying to instigate a possible conflict, especially a military conflict,” Kim Brown, a Voice of Russia host and analyst, told RT. “Is the best way to react to this to send American troops [to] yet another country thousands of miles away? I don’t think so.”Meanwhile, the Pentagon has said the alleged plot requires a diplomatic and legal response, lowering the possibility of military action.The US Treasury Department has already imposed new sanctions on Iranian commercial airline Mahan Air over the alleged Iranian plot to assassinate the Saudi ambassador at a restaurant in Washington.The alleged plot, which involved the attempted bombing of an unnamed restaurant by a Mexican drug cartel in the pay of Iran, was revealed on Tuesday in a criminal complaint filed in a federal court in New York. The assassination is said to have been foiled because the mobsters’ agent was a US informant.Several US and Saudi officials have pointed fingers at the Quds Force, the military intelligence department of Iran’s Revolutionary Guard, as the architects of the would-be crime.Attorney-General Eric Holder, in announcing the criminal charges, said the plot was “directed and approved by elements of the Iranian government,” and the Quds Force specifically.Prince Turki bin Faisal Al Saud, a former Saudi ambassador to the US, said the burden of evidence against Iran is "owerwhelming". He added somebody in Iran will have to pay for the suspected crime.Tehran strongly denies the allegations, insisting they are absolutely false, and complaining of being targeted by Washington in a smear campaign.The accusations filed to the US court are “a continuation of the old American-Zionist hostile policy toward the Islamic Republic,” a statement of the Iranian Foreign Ministry says.“Inventing such tales is aimed at splitting Islamic society and saving the Israeli regime from the dead end it has come to,” ministerial spokesman Ramin Mehmanparsat said.The official added that the diplomatic scandal was brought to light against the backdrop of a growing protest movement in the US and the Middle East.Earlier, Iran’s Ambassador to the UN, Mohammad Khazaee, sent an official complaint to Secretary General Ban Ki-moon over the allegations. He stressed that Iran has no involvement with terrorism and, on the contrary, has itself been the victim of terrorist attacks, including the killing of several nuclear scientists over the last two years. ­Plot sting in play The US has charged two people with conspiracy to murder the Saudi ambassador to Washington, Adel al-Jubeir. One of them, Manssor Arbabsiar, a 56-year-old naturalized US citizen, is said to have tried to hire a Mexican hit squad to bomb the diplomat. He is currently under arrest. His alleged contact in the Revolutionary Corps, Gholam Shakuri, is at large in Iran.Arbabsiar said he was asked to organize the killing by his cousin, Abdul Reza Shahlai, who holds a senior position in the Quds Force.The plot, which was allegedly put into motion in late May, was known to American agents from the very beginning. Arbabsiar was arrested in late September in New York and has reportedly co-operated with law enforcers.In late September during a trip to Saudi Arabia, President Barack Obama's adviser briefed King Abdullah about an alleged Iranian plot against the Saudi ambassador in the United States. National security adviser Tom Donilon and the Saudi monarch discussed the intelligence operation which led to charges on Tuesday, Reuters news agency reported. ­Foad Izadi, Professor of political communication at Tehran University, says the scant information made public by the US simply does not make sense.“It doesn’t make sense for the Iranian government to hire someone who has been in jail in the US and has been an informant to the US government. And why would Iran want to kill the Saudi Arabian ambassador in the US with all their security apparatus and the level of intelligence existing in the US?” he asked. “The location, the person who was supposed to be killed, and the person who was supposed to do the killing, all raise very difficult questions,” he said, adding that a similar alleged plot by Saddam Hussein’s government to kill President George Bush in Kuwait springs to mind.