BEIRUT – Syria's prime minister began planning his break from the regime two months ago when Bashar Assad offered him the post and an ultimatum: Take the job or die.

The full scope of Riad Hijab's carefully executed flight to the rebel side – described by an aide who escaped with him to Jordan – reverberated Monday through Syria's leadership. Hijab became the highest-ranking government official to defect, emboldening the opposition and raising fresh questions about the regime's ability to survive the civil war.

Although Assad has been hit by a string of embarrassing defections of military and political figures, they have yet to cause visible changes in the regime's abilities on the battlefield. The loss of high-profile government officials, however, suggests fissures are reaching deeper into the ruling system and could force Assad to retreat further behind a cadre of loyalists as fighting flares on several fronts.