“Military action will bring great costs for the region,” Rouhani said, and “it is necessary to apply all efforts to prevent it.”

Gen. Mohammad Ali Jafari, chief of Iran’s powerful Revolutionary Guards, told the Tasnim news website, that an attack on Syria “means the immediate destruction of Israel.”

The statements came as Russia asked for an urgent meeting on Syria at the United Nations Security Council, the Associated Press reported, citing a U.N. diplomat.

Russian state-owned media reported Thursday that two Russian warships were sailing for the eastern Mediterranean Sea to protect Russian interests as tensions escalate in the region.

The ships, a missile cruiser and a large anti-submarine vessel, are traveling from the North Atlantic and will arrive in a number of days, Reuters reported.

Harmer said the ships may resupply Assad’s forces or evacuate more Russian citizens or Russian materiel from its navy base at the Syrian port of Tartous.

But as far as taking on U.S. Navy, “they’re not built for that,” Harmer said.

Iran and Syria have threatened to retaliate against Israel and other U.S. allies in the Middle East in the event of a U.S. attack on Syria. Both countries have rockets that can reach Israel and U.S. allies in the Persian Gulf. Iran’s Islamic Revolutionary Guard Corps and its proxy, the Lebanese Shiite terror group, Hezbollah, have world-wide network it can use to target countries that support the military strike.

Hundreds of Syrians were killed Aug. 21 in an attack that the Syrian opposition and the White House attribute to chemical weapons.

U.S. intelligence reports support “two facts,” State Department spokeswoman Marie Harf told reporters Thursday: “First that chemical weapons were used August 21 in Syria, and that the Assad regime is responsible for that use.”

President Obama said Thursday he has not made a decision on whether to launch what he called “a shot across the bow” that would send a message to Syria it “better not do it again.”

Iran’s reaction would depend on the scale of any U.S. attack, and it may not react at all, says Karim Sadjapour, an Iran expert at the Carnegie Endowment for International Peace, who has has high-level contacts in the Iranian regime.

“Iran talks about Syria in the same way the U.S. talks about Israel, (as) an indispensable regional ally whose national security is sacrosanct,” Sadjapour said. But “it’s unclear whether Tehran would see it in their interests to go to war. Especially if a U.S. military attack is intended only to bruise, not end, the Assad regime.”

Iran has provided Syrian President Bashar al-Assad billions of dollars to prosecute his civil war, which the United Nations says has killed more than 100,000 Syrians so far, Sadjapour said.

Iran has also sent militia members and its Iranian Revolutionary Guards Corps to fight alongside and in command of Syrian government troops, according to Phillip Smyth, who documents Shiite militias fighting in Syria on the Jihadology web site. Smyth says dozens of active or allegedly-retired members of the Iranian Revolutionary Guard Corps have been killed in the Syrian fighting.

But Iranian threats to help Syria against the USA is a bluff, Harmer said.

“The Iranians aren’t going to do anything here,” Harmer said.

While Iran may want to retaliate, it usually does so through Hezbollah, which “is task saturated between helping Assad stay in power, and protecting Shia neighborhoods in Beirut from retaliatory car bombs,” Harmer said. “I don’t think Iran can run the risk of retaliating on their own.”

The last time Hezbollah launched a barrage of rockets against Israel, in 2006, it suffered a withering counter attack and ground invasion that left its rocket stores decimated, its villages in southern Lebanon badly damaged and its infrastructure in Beirut in shambles.

And the last Last time Iran faced the USA was in the 1980s during the “Tanker War” in the Persian Gulf, when Iran and Iraq, at war with each other, targeted ships serving the other country.

Iran attacked U.S. flagged tankers and suffered extensive damage to several Iranian patrol boats and other military ships without inflicting any damage on the U.S. military vessels, Harmer said.

“The Iranians have experience with the United States. It hasn’t gone well for them,” he said. “They are not going to do so in reaction to a U.S. strike on Syria.”

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