Senior U.S. politicians and a Saudia Arabian prince called Wednesday for Iran to be held accountable for an alleged plot to assassinate the Saudi ambassador to the United States.
A diplomat told Reuters that the U.S. and Saudia Arabia were considering taking the matter to the United Nations Security Council.
House Speaker John Boehner told reporters that the plot was "a very serious breach of international behavior."
Speaking of the Iranian government, Boehner said the U.S. should "hold their feet to the fire."
However, he added, "I don't think I need to be specific in terms of what the administration could or should do."
U.S. authorities said Tuesday they had broken up plans by two men linked to Iran's security agencies to assassinate Saudi Ambassador Adel al-Jubeir in Washington. They said it was foiled when the men tried to hire a hitman — a U.S. informant who was posing as a member of a Mexican drug cartel — to kill the diplomat with a bomb.
One suspect was arrested last month while the other is believed to be in Iran.
The motive for the alleged plot was not clear. Iran has in the past assassinated its own dissidents abroad, but an attempt to kill an ambassador would be a highly unusual departure.
U.S. officials said Wednesday it was "more than likely'' that Iran's supreme leader and the head of its Quds force knew of the alleged plot. The officials, speaking on condition of anonymity, also said it was quite possible that Iran's president, Mahmoud Ahmadinejad, did not know of the alleged plan.
Iran's supreme leader is Ayatollah Ali Khamenei.
'Childish and amateur game'Iran has strongly denied the allegation.
Parliament speaker Ali Larijani, echoing Iran's official stance, said the allegation was a "mischievous, foolish" attempt to fuel tension between Tehran and Riyadh.
"These claims are vulgar ... It is a childish and amateur game ... We believe that our neighbors in the region are very well aware that America is using this story to ruin our relationship with Saudi Arabia," Larijani told parliament Wednesday in a speech broadcast live on state radio.
However, the Saudi prince, Turki al-Faisal, a senior member of the royal family and a former ambassador to Washington, said in London Wednesday that he had no doubt Iran was behind the plot.
"The burden of proof is overwhelming... and clearly shows official Iranian responsibility for this," he said. "Somebody in Iran will have to pay the price."
Vice President Joe Biden echoed those hawkish sentiments, telling ABC News that Iran would be held accountable.
He said Washington was working for a new round of international sanctions against Iran, warning that "nothing has been taken off the table."
A Western diplomat told Reuters Wednesday that the United States was talking to Saudi Arabia and other allies about the matter.
"The United States and Saudi Arabia and other allies are discussing the possibility of taking this to the Security Council because this is an assault on a foreign diplomat in the U.S.," said the diplomat, who is familiar with such discussions.
The diplomat said formal talks were likely to begin on Wednesday but did not say whether any party would seek a resolution, sanctions or any other action.
"The U.S. is taking this very seriously," the diplomatic source said.
Military confrontation looms?Iranian analyst Saaed Leylaz said it was hard to see why Iran would risk involving itself in such a plot.
"Killing the Saudi envoy in America has no benefit for Iran," he said. "The consequences of this plot are dangerous ... It could cause military confrontation in 2012 between Iran and America."
The Obama administration has already begun its effort to further isolate Iran internationally by instructing U.S. diplomats abroad to tell their host governments about the plot. Ambassador to the United Nations Susan Rice was to individually brief members of the Security Council on Wednesday.
U.S. officials said the State Department had sent a cable classified as "secret" to all American embassies and consulates around the world telling them to put the case against Iran before foreign authorities.
The officials, who spoke on condition of anonymity to describe the classified cable, said the document asks nations to consider appropriate steps in response to the alleged scheme, which has been described by President Barack Obama as "a flagrant violation of U.S. and international law." It does not, however, suggest any specific measures, the officials said.
Iran and Saudi Arabia, a U.S. ally, are regional rivals. The United States and other powers are putting pressure on Iran to abandon a nuclear program which they believe is aimed at developing nuclear arms. Iran has denied having such ambitions.
However countries such as Saudi Arabia and Israel have feared that Washington could take its eye off the ball on Iran. U.S. diplomatic cables from Riyadh leaked by Wikileaks over the past year — in which Jubeir features prominently — show Riyadh repeatedly pushing the United States to take a tougher stand, including the possible use of military force.
Tensions rose between Riyadh and Tehran when Saudi Arabia sent troops to help Bahrain put down pro-democracy protests let by the island state's Shiite majority that both governments accused Iran, a non-Arab Shiite state, of fomenting.
This month Riyadh accused some among its Shiite Muslim minority of conspiring with a foreign power — a reference to Iran — to cause instability, following street clashes in the Eastern Province.
Global travel alertThe State Department issued a three-month worldwide travel alert for American citizens, warning of the potential for anti-U.S. action, including within the United States.
"The U.S. government assesses that this Iranian-backed plan to assassinate the Saudi ambassador may indicate a more aggressive focus by the Iranian government on terrorist activity against diplomats from certain countries, to include possible attacks in the United States," it said in a statement.
At a news conference Tuesday, FBI Director Robert Mueller said a convoluted plot involving monitored international calls, Mexican drug money and an attempt to blow up the ambassador in a Washington restaurant smacked of a Hollywood movie.
Attorney-General Eric Holder tied it to the Islamic Revolutionary Guard Corps (IRGC), guardian of Iran's 1979 revolution, and the Quds Force, its covert, operational arm.
"I think one has to be concerned about the chilling nature of what the Iranian government attempted to do here," he said.
The primary evidence linking Iran to the alleged conspiracy is that the arrested suspect is said to have told U.S. law enforcement agents that he had been recruited and directed by men he understood were senior Quds Force officials.
U.S. officials identified the two alleged plotters as Gholam Shakuri, said to be a member of the Quds Force, who is believed to be at large in Iran, and Manssor Arbabsiar, who was arrested on September 29 when he arrived at John F. Kennedy International Airport from Mexico.
Detained man 'no mastermind'Arbabsiar, 56, a naturalized U.S. citizen with an Iranian passport, initially cooperated with authorities after being arrested with help from the informant. He made calls to Shakuri after being arrested and acted as if the plot was still a go, court documents said.
As part of the plot, the informant talked to Arbabsiar about trying to kill the ambassador at a Washington, D.C. restaurant he frequented, but warned him that could lead to dozens of others being killed, including U.S. lawmakers.
The criminal complaint said that Arbabsiar responded "no problem" and "no big deal."
In a monitored call, Shakuri told Arbabsiar to execute the plot, saying "just do it quickly, it's late," court papers say.
Arbabsiar appeared briefly in a Manhattan courtroom on Tuesday where he was ordered detained and assigned a public defender. He appeared in blue jeans and a dress shirt, with thinning gray hair and a scar on the left side of his face.
A friend and one-time business partner of Arbabsiar, David Tomscha, said Arbabsiar, known as Jack to his friends, made an unlikely secret agent.
Tomscha said Arbabsiar was likeable, but a bit lazy and " no mastermind."
"I can't imagine him thinking up a plan like that. I mean, he didn't seem all that political. He was more of a businessman ... He was sort of a hustler," he said.