By David Rosenberg

Riyadh, Saudi Arabia

Many analysts remain skeptical about U.S. charges that Iran plotted to assassinate the Saudi ambassador in Washington, but in Riyadh officials are taking the accusations seriously and have already begun to employ them in a diplomatic assault against Tehran.

On Sunday, Riyadh's permanent mission to the United Nations formally requested that the secretary-general notify the Security Council of the "heinous conspiracy" against it, Saudi-owned newspapers reported on Sunday. The move could be used to impose fresh sanctions on Iran.

"Tension is already high and is going to skyrocket in the days and weeks to come," Abdelkhaleq Abdalla, professor of political science at Emirates University in Dubai, told The Media Line. "How far will the Saudis go? Maybe as far as recalling their ambassador from Tehran. I think this is the limit."

A long-standing rivalry between the two countries has grown more acrimonious as the turmoil of the Arab Spring topples governments and threatens others. The unrest has raised deep fears in Saudi Arabia that it or its Gulf neighbors could be next. In Iran, the initial euphoria of seeing old adversaries like Egyptian President Husni Mubarak fall has given away to concerns that allies like Syria's Bashar Al-Assad are also jeopardy.

The U.S. charges, leveled last week, involve a plot to assassinate Saudi Ambassador Adel Al-Jubeir in a conspiracy involving a secret Iranian military unit, the Quds force, and an Iranian living in the U.S. Critics have termed the charges implausible because the operation as described by the U.S. government appears so ham-fisted and without any obvious benefit to the Iranian regime.

Tehran has vehemently denied the charges, but in Saudi Arabia, officials have expressed deep anger.

"Somebody in Iran will have to pay the price," Saudi Prince Turki Al-Faisal, often seen as an unofficial foreign policy voice for the royal family, said in London on Wednesday. "The burden of proof and the amount of evidence in the case is overwhelming and clearly shows official Iranian responsibility for it."

Iran's Foreign Minister Ali Akbar Salehi on Saturday urged Riyadh to exercise caution in moving against Iran, asserting that "the [U.S.] enemy always seeks to sow discord" in the region even while conceding that Tehran has differences with Riyadh. "We have no problem with Saudi Arabia, but there are some differences of opinion as to regional developments," he said in an interview with a local radio station and reported in the Tehran Times.

Abdalla said Tehran may retaliate by recalling its ambassador to Riyadh, but is likely to be careful not to ratchet up the situation any more than it has. Other Saudi actions could include limiting Iranian visas for the Haj pilgrimage to Mecca, which begins later this month.

The two countries are divided by religion and politics, with Saudi Arabia seeing itself as the standard bearer of Sunni Islam and the defender of the Muslim world's status quo while Shiite Iran's leadership views itself as the vanguard of Islamic revolution. The two sides have bumped heads in places as far afield as Lebanon and the Gaza Strip, but the stakes have grown this year amid the chaos enveloping the Middle East.

Protests in February by the Shiite majority against a Sunni monarchy in Bahrain, an island emirate just off the Gulf coast from Saudi Arabia, were seen in Riyadh as evidence of Iranian meddling and prompted it to send it forces to quash the rebellion. Earlier this month, the Saudi Interior Ministry accused an unnamed foreign power -- a code word for Iran -- of instigating riots by Shiites in the country's eastern province.

Many analysts and governments have expressed doubt about the U.S. allegations, which fingers an Iranian-American used car salesman as the key figure in the case. Abdalla said he was withholding judgment until details are clarified. However, he also noted that U.S. credibility had suffered from what ultimately proved to be false charges that Iraq under Saddam Hussein was developing weapons of mass destruction. Those charges were used as a justification for launching the war against Iraq in 2003.

But Michael Singh, an analyst at the Washington Institute for Near East Policy, termed the Iranian assassination plot "entirely plausible." He cited the disbursed command structure of the Quds force, a unit of the Islamic Revolutionary Guard Corps (IRGC). That gives more room for lower-level commanders to make key - and perhaps amateurish - decisions, he said.

The humiliation Iran felt at not being able to counter Saudi moves in Bahrain would give Iran ample reason to strike out at the Saudi embassy, echoing tactics it employed in the 1990s when the IRGC allegedly attacked Israeli embassy in Argentina in 1994.

Saudi Arabia won't be alone in its drive against Iran. U.S. President Barack Obama said last week he would press for "the toughest possible sanctions" against Iran over the alleged plot and vowed not to take any options off the table, a phrase used to mean the possibility of using force. Singh said the U.S. could not rely solely on sanctions.

"Responding only with sanctions would be a mistake," he wrote on last week. "By downplaying the U.S. military option against Iran and ceasing military signaling activities in the Gulf, the Obama administration has allowed American deterrence of Iran to deteriorate. Reestablishing that deterrence is vital to discouraging IRGC activities such as this plot."

The New York Times reported that Obama is pressing UN nuclear inspectors to release classified intelligence showing that Iran is designing and experimenting with nuclear weapons technology. Over the longer term, several senior Obama administration officials said in interviews, they are mulling a ban on financial transactions with Iran's central bank and an expansion of the ban on the purchase of petroleum products sold by IRGC-affiliated companies.

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