Iran threatens payback on Syria; Russia sends warships

Iran and Russia are working together to prevent a Western military attack on Syria. Russia even sent warships to the Mediterranean where U.S. destroyers are in position to strike if ordered.

Military analysts said Syria's allies' options to stop the United States or make it pay a price after a strike are limited.

"The Russians can help Syria politically and diplomatically in the United Nations and provide supplies, but they're not nearly as capable as they were at the end of the Cold War," said Chris Harmer, an analyst at the Institute for the Study of War who worked on military plans for the Persian Gulf as a commander in the Navy.

Although Iran may want to retaliate, it usually does so through the Lebanese Shiite terror group Hezbollah, which "is task-saturated between helping (Bashar) Assad stay in power and protecting (Shiite) neighborhoods in Beirut from retaliatory car bombs," Harmer said. "I don't think Iran can run the risk of retaliating on their own."

Other analysts, such as Phillip Smyth, who documents Shiite militias fighting in Syria on the Jihadology website, said that although Syrian President Assad's forces and Hezbollah may be stretched thin in Syria and Lebanon, Iran's ability to retaliate should not be counted out.

In the 1980s, while Iran was fighting a major war with Iraq, it sent hundreds of members of its Revolutionary Guards to southern Lebanon and built Hezbollah to counter Israel and the United States, Smyth said. Hezbollah's bombings of the U.S. Embassy and the U.S. Marine Corps barracks in Beirut killed 58 American diplomats and Lebanese citizens and 241 Marines in 1983.

On Thursday, Iranian President Hassan Rouhani said in statements carried by several Iranian state-controlled media outlets that Iran and Russia would work in "extensive cooperation" to prevent any military action against Syria. Western military action against Syria would be an "open violation" of international laws, Rouhani said.

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