Pentagon leaders told Congress on Thursday that they had supported a recommendation to arm Syrian rebels promoted by the State Department and CIA but which was reportedly rebuffed by the White House.
President Barack Obama's government has limited its support to non-lethal aid for the rebels who, despite receiving weapons from countries like Qatar and Saudi Arabia, are poorly armed compared to Syrian President Bashar al-Assad's army and loyalist militias.
Syria's 22-month-long conflict has killed an estimated 60,000 people.
Senator John McCain, a Republican from Arizona, has championed greater U.S. involvement and chided the Obama administration at a hearing, asking Pentagon leaders: "How many more have to die before you recommend military action?"
He then asked Defense Secretary Leon Panetta and General Martin Dempsey, the chairman of the U.S. military's Joint Chiefs of Staff, whether they backed the recommendation by the State Department and CIA chiefs last year to arm the rebels.
"We do," Panetta said. "We did," Dempsey chimed in.
The comments were the first public acknowledgement of Pentagon support since the New York Times reported on Feb. 2 about the plan developed last summer by Hillary Clinton and David Petraeus, who have since left their jobs at the State Department and CIA, respectively.
The defense chiefs' testimony suggests that the heads of most major U.S. foreign policy and security agencies - the State and Defense departments, and the CIA - jointly backed the plan, but ran into White House opposition.
The Times said that the plan to arm and train rebels was rebuffed by the White House, which was concerned it could draw the United States into the Syrian conflict and that the arms could fall into the wrong hands.