The White House knocked down a proposal last summer from top national security leaders, including then-Secretary of State Hillary Clinton and CIA Director David Petraeus, to arm Syrian rebels, according to U.S. officials, one of whom said the issue appears dead for now.

Defense Secretary Leon Panetta and Joint Chiefs Chairman Martin Dempsey said in testimony to a Senate committee on Thursday that they also backed the plan to provide weapons to opposition fighters.

But officials, who requested anonymity to speak freely about a sensitive subject, said the White House rejected the idea.

"The reason we have not armed them is because the White House has no appetite for it," a U.S. official familiar with the deliberations told CNN.

The official said the ambassador to Syria, Robert Ford, was among those in the State Department who "advocated for it pretty strongly."

The issue of arming the rebels "is dead in the water for now because folks are resigned to the fact that White House will not budge," the official added.

The White House and the State Department declined to comment on the matter.

The Obama administration has resisted arming the rebels, citing concerns about the infiltration of extremists groups who could possibly use those weapons against other targets.

For now, the U.S. government has provided millions in humanitarian aid to the rebels fighting the regime of Syrian President Bashar al-Assad.

The CIA has also sent agents to vet the opposition group to try to better understand its composition.