Most analysts expect Iran to respond to any attack on Syria. But the kind of retaliation detailed in this Wall Street Journal article can be seen as escalating beyond anyone's ability to control:

The U.S. has intercepted an order from Iran to militants in Iraq to attack the U.S. Embassy and other American interests in Baghdad in the event of a strike on Syria, officials said, amid an expanding array of reprisal threats across the region.

Military officials have been trying to predict the range of possible responses from Syria, Iran and their allies. U.S. officials said they are on alert for Iran's fleet of small, fast boats in the Persian Gulf, where American warships are positioned. U.S. officials also fear Hezbollah could attack the U.S. Embassy in Beirut.

While the U.S. has moved military resources in the region for a possible strike, it has other assets in the area that would be ready to respond to any reprisals by Syria, Iran or its allies.

Those deployments include a strike group of the USS Nimitz aircraft carrier and three destroyers in the Red Sea, and an amphibious ship, the USS San Antonio, in the Eastern Mediterranean, which would help with any evacuations.

The U.S. military has also readied Marines and other assets to aid evacuation of diplomatic compounds if needed, and the State Department began making preparations last week for potential retaliation against U.S. embassies and other interests in the Middle East and North Africa.

U.S. officials began planning for a possible strike on Syrian regime assets after the Aug. 21 attack outside Damascus in which the U.S. says Syrian government forces killed over 1,400 people using chemical weapons. The U.S. military has prepared options for an attack and beefed up its military resources in the region, including positioning four destroyers in the Eastern Mediterranean.

That process slowed last weekend when President Barack Obama said he would first seek an authorization for using military force from Congress.

A delay in a U.S. strike would increase opportunities for coordinated retaliation by groups allied with the Assad government, including Shiite militias in Iraq, according to U.S. officials.

Iraqi insurgents targeting our embassy in Baghdad is one thing. We can pretend that Iran had nothing to do with an attack of that nature and won't have to respond.

But Hezb'allah attacking our embassy in Beirut? That would require a military response by the US given the Hez's well known close relationship with Tehran. Before you know it, it's an eye for an eye until the whole world goes blind. As the Israelis could tell us, that kind of tit for tat response is usually counterproductive and could easily lead to widening the war.

That's why Iran will probably stick to unleashing its terrorist proxies in Iraq. Any retaliation that has their fingerprints in plain view would be met with a response from us that they want no part of.