Syria conflict: Will the US plan to arm the rebels work?
Syria has dismissed as "a caravan of lies" claims that it used chemical weapons, after the US said it would give the rebels "direct military aid".
President Barack Obama's decision came after the White House said it had clear evidence of government forces carrying out small-scale chemical attacks.
However, the Syrian leader is receiving backing from parts of the wider region, including Iran, Russia and Hezbollah, reducing the likelihood of him negotiating a transition of power.
Middle East editor Jeremy Bowen reports from Beirut.