Separately, members of the House Intelligence Committee who had balked weeks ago at the Obama administration's first attempt to pay for lethal aid for the Syrian rebels said Monday that their concerns largely had been addressed.
"After much discussion and review, we got a consensus that we could move forward with what the administration's plans and intentions are in Syria consistent with committee reservations," Rogers said in a statement.
Dempsey spelled out costs, ranging from millions to billions of dollars, for options that included training and arming vetted rebel groups, conducting limited strikes on Syria's air defenses, creating a no-fly zone, establishing a buffer zone and controlling Syria's massive stockpile of chemical weapons.
The military leader said that while these steps would help the opposition and pressure Assad's government, "We have learned from the past 10 years, however, that it is not enough to simply alter the balance of military power without careful consideration of what is necessary in order to preserve a functioning state."
Dempsey's reference was to the more than a decade of war in Iraq and Afghanistan.
The Joint Chiefs chairman said creation of a no-fly zone would neutralize Syria's air defenses. It would require "hundreds of ground and sea-based aircraft, intelligence and electronic warfare support, and enablers for refueling and communications. Estimated costs are $500 million initially, averaging as much as a billion dollars per month over the course of a year."