US to help rebels after Syrian forces 'cross red line'
14 June 2013 Last updated at 06:57 BST
The United States says it is increasing the scope and scale of military support for opposition forces in Syria after it concluded that President Assad's forces had used chemical weapons - including the nerve agent, sarin.
The White House estimates that between 100 and 150 people have died from detected chemical attacks in Syria to date.
David Willis reports from Washington.