What prompted Syria's clashes in Assad's strongholds?

Troops from Syria's interim government are battling forces loyal to ousted leader Bashar al-Assad in coastal cities in the west of the country. The UK-based Syrian Observatory for Human Rights says that more than 200 people have been killed since fighting broke out on Thursday - and has reported cases of executions. Syria's new government has deployed more forces to the affected areas and imposed a curfew.