An Associated Press analysis shows the staggering cost of every stage of an attack on Syria:
It is not uncommon for U.S. forces to open an assault by launching scores of Tomahawk missiles costing over $1 million apiece and dropping bombs from radar-evading B-2 planes that fly 18 hours each way from their base at a cost of $60,000 an hour.
"I was surprised when I heard him (Hagel) say tens of millions of dollars. That's low-balling it," said Todd Harrison, a defense budget analyst at the Center for Strategic and Budgetary Assessments.
The U.S. Navy fired 221 Tomahawks in operations against Libyan leader Muammar Gaddafi in 2011, nearly half of them - 110 - in an opening salvo against 22 Libyan military targets, including air defenses, communications and command structures.
If U.S. forces used a similar number of missiles to hit Syrian targets related to chemical weapons use by President Bashar al-Assad's forces, the cost would top $100 million.
[Admiral Jonathan] Greenert said it costs about $25 million a week for a carrier strike group in routine operations. If the carrier was used in military operations, the cost would rise to $40 million a week as a result of longer flight hours for its planes.