Obama warns Assad on chemical weapons
US President Barack Obama has warned Syria that the use of chemical weapons would be a "red line" that would change his thinking on intervention in the crisis.
Speaking to reporters at a White House briefing, he said the deployment or use of chemical weapons would widen the conflict in the region.
He also added that he had "at this point not ordered military engagement".
Jane O'Brien reports from Washington.
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21 Aug 2012