Senator John McCain, an influential Republican, called Monday for US air strikes on Syrian forces to protect population centers and create safe havens for opponents of the regime.
"To be clear: This will require the United States to suppress enemy air defenses in at least part of the country," McCain said in remarks on the floor of the Senate.
McCain argued it would be a 'strategic and moral defeat' for the United States if Syrian President Bashar al-Assad succeeds in clinging to power, and said military action was needed to drive a negotiated transition.
"What opposition groups in Syria need most urgently is relief from Assad's tank and artillery sieges in the many cities that are still contested," he said.
"Providing military assistance to the Free Syrian Army and other opposition groups is necessary, but at this late hour, that alone will not be sufficient to stop the slaughter and save innocent lives.
"The only realistic way to do so is with foreign air power," he said.
At the request of the Syrian opposition, McCain said, "The United States should lead an international effort to protect key population centers in Syria, especially in the north, through airstrikes on Assad's forces."
He said the safe havens protected by air power would allow the Free Syrian Army and other armed groups to train and organize themselves, and enable the delivery of humanitarian and military assistance.