BEIRUT – The Syrian regime appears to have absorbed the shock it suffered in the heaviest blow against it yet in Syria’s 17-month-old upheaval – a bombing that killed four top aides.

The blast raised opponents’ hopes that President Bashar Assad could fall soon. Instead he is back on the offensive and has reshuffled his inner circle of loyalists to brace for a long battle in what has become an outright civil war.

Although the president is embattled, he remains surrounded by loyal generals, many who are inextricably tied to the regime and have played a key role in the brutal crackdown against the opposition.