Physics teaches us that every action has an equal and opposite reaction.  That isn’t always true in diplomacy, but it’s usually dangerous to assume it won’t.  Thanks to the beating of war drums over Syria, the US has ordered the evacuation of non-essential diplomatic personnel from yet another country in the Middle East:

The State Department on Friday ordered nonessential U.S. diplomats to leave Lebanon due to security concerns as the Obama administration and Congress debate military strikes on neighboring Syria.

In a new travel warning for Lebanon, the department said it had instructed nonessential staffers to leave Beirut and urged private American citizens to depart Lebanon.

The step had been under consideration since last week when President Barack Obama said he was contemplating military action against the Syrian government for its alleged chemical weapons attack last month that the administration said killed more than 1,400 people near Damascus.

“The potential in Lebanon for a spontaneous upsurge in violence remains,” the department said.

Hezbollah has aligned itself with Bashar al-Assad in Syria and is fighting on the regime’s side.  It’s possible and even probable that American strikes on Syrian military positions will either inadvertently or purposefully target Hezbollah positions.  That would create an opening for Hezbollah in Lebanon to expand the war by attacking American and Western interests in their home country, a step that its patrons in Iran would certainly not hesitate to take.

Speaking of Iran, they’re targeting another American embassy for retaliation, according to messages intercepted by US intel. They may also target US Navay assets near the Straits of Hormuz in the Persian Gulf:

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. …

The U.S.is also pulling diplomats out of Adana, Turkey and is recommending that U.S. citizens “defer nonessential travel” to southeastern Turkey.

And the Russians aren’t just sitting around, either:

Three Russian naval ships were sailing toward Syria in the eastern Mediterranean on Friday and a fourth was on its way, the Interfax news agency reported, citing a source at navy headquarters.

Kremlin chief of staff Sergei Ivanov said Thursday that Russia was boosting its naval presence in the Mediterranean Sea, but primarily in order to organize a possible evacuation of Russians from Syria. He did not say how many vessels were being sent.

The prospect of increased Russian naval presence near Syria has stoked fears of a larger international conflict if the United States orders airstrikes over an Aug. 21 chemical weapons attack in a suburb of Damascus, the Syrian capital. The U.S. already has numerous war ships in the Mediterranean.

Two Russian amphibious landing vessels and a reconnaissance ship have passed through the Dardanelles strait, according to the report carried by Interfax, a privately owned agency known for its independent contacts within Russia’s armed forces.

The worst possible outcome from the Syrian civil war is its expansion into a regional war that pulls the US and Russia in on opposite sides.  American intervention all but guarantees that outcome.