Washington The challenge for the CIA increased when the United States shut its embassy in Damascus last month.
The facility had provided diplomatic cover for agency officers and a base for intelligence-gathering operations inside Syria's capital.
US President Barack Obama has refrained from issuing a classified "finding" that would give the CIA authority to conduct covert operations inside Syria against Al Assad, US officials said. Even in its core mission of gathering intelligence, the agency has been cautious, according to officials who described Syria as a sophisticated counter-intelligence adversary, with substantial assistance from Iran.
No agency teams were sent to meet with opposition elements in Homs before that city became the target of a violent crackdown by Al Assad's forces. And officials said no surveillance drones have been deployed over Syria, whose air defences are considered more than capable of shooting down unmanned aircraft. Instead, the US agencies have had to monitor events from higher altitudes.
The US ambassador to Syria, Robert Ford, now based at the State Department in Washington, this week posted what he described as "declassified" American satellite images on a US Embassy Facebook page to call attention to the "disproportionate nature of the Al Assad regime's violence against the people and his willingness to attack civilian targets."