Syria's Bashar al-Assad firmly in control, U.S. intelligence officials say Assad "is very much in charge," said a senior U.S. intelligence official responsible for tracking the conflict, adding that Assad and his inner circle seem convinced that the rebellion is being driven by external foes and that they are equipped to withstand all but a large-scale military intervention. "That leadership is going to fight very hard," the official said. Over the long term, "the odds are against them," he said, "but they are going to fight very hard." The comments, provided by three intelligence officials on the condition of anonymity to share candid assessments, were the most detailed to date by U.S. analysts on the status of the uprising, which began last March. The officials said the regime's tactics have taken a more aggressive turn and released newly declassified satellite images on Friday showing what officials described as "indiscriminate" artillery damage to schools, mosques and other facilities in the beleaguered city of Homs in recent weeks. Overall, they described Syria as a formidable military power, with 330,000 active-duty soldiers, surveillance drones supplied by Iran and a dense network of air defense installations that would make it difficult for the United States or other powers to establish a no-fly zone. "This is an army that was built for a land war with the Israelis," said a second senior U.S. intelligence official. After hesitating to attack civilian population centers earlier in the conflict, the regime's "restraint . . . has been lifted," the official said. Syrian forces continued their month-long shelling of the opposition stronghold of Homs, in the west-central part of the country, on Friday, according to news reports. Thousands demonstrated in other parts of the country in anticipation of the scheduled arrival of Kofi Annan, the special envoy of the United Nations and Arab League, in Damascus on Saturday. He is expected to meet with Assad. U.N. humanitarian chief Valerie Amos, who visited Homs this week, said she was "devastated" by what she saw in the ravaged city. "There are no people left," she said. Amos, speaking in Turkey after visiting refugee camps along the Syrian border, said the Assad government had agreed to a "limited assessment" of humanitarian needs but had refused "unhindered" access for aid organizations and "asked for more time" to consider U.N. proposals for extended assistance for civilians. In Washington, the intelligence officials cited a number of factors protecting the regime from collapse. Not least among them is the level of motivation in an inner circle convinced that yielding power will mean death or life imprisonment.