Syria unrest: US calls on President Assad to resign
US President Obama has called for Syrian President Bashar al-Assad to resign, joining the UK, France, Germany and the EU in demanding he step down.
Mr Obama has also signed an order tightening US sanctions on Syria.
US Secretary of State Hillary Clinton said Mr Assad was the main obstacle to his people enjoying a "government that respects their dignity, protects their rights, and lives up to their aspirations".