Not cheap.
After a decade of massively expensive war, it's not unreasonable to ask
how much bombing Syria would cost. But the responses to that question ... those are unreasonable. First off, you have Republicans suddenly concerned about military spending:
[H]awkish Republicans, traditionally supportive of military might, are balking at the prospect of authorizing force against the regime of Syrian President Bashar Assad amid sequestration and other spending cuts that have forced the Pentagon to scale back training, furlough civilian employees and defer ship maintenance.
“Our military has no money left,” complained Oklahoma Sen. Jim Inhofe, the top Republican on the Senate Armed Services Committee.
Okay, guys, you do know you caused sequestration and could end it, right? And you do remember all the times over the past 10 years when the military would have had no money left ("no money" being an extremely relative concept here) and you appropriated massive amounts of money so that George W. Bush could continue throwing not just dollars but American lives into his wars, right? If not, it's not just the dynamic of the Congress as a whole that's completely broken, but apparently the brains of individual Republicans in Congress.
Then you have the Obama administration:
The Pentagon declined to provide POLITICO detailed cost estimates for its attack plans. Nonetheless, Defense Secretary Chuck Hagel offered some clues on Wednesday in his testimony before the House Foreign Affairs Committee. The options being considered, he said, “would be in the tens of millions of dollars — that kind of range.”
A U.S. official, discussing Hagel’s remarks on the condition of not being identified, offered this clarification: “Tens of millions is conceivable, but it could be a bit higher based on current estimates.”
With a single Tomahawk missile costing $1.5 million, a week's operation of a guided missile destroyer costing $2 million, and extended operations of a carrier strike group costing $40 million a week, either Hagel and the "official" are lying, or President Obama really might as well just send that
sternly worded letter. That wouldn't cost even tens of millions of dollars, wouldn't kill anyone, and wouldn't do a whole lot less damage to Assad's ability to kill his own people.