The US Secretary of State says Syria's use of chemical weapons crosses a "global red line."
John Kerry has arrived in Britain to gain support for military action against the country.
His mission comes as the Syrian President once again warned he'll retaliate if the country is attacked over the issue of chemical weapons.
Survivors of the attack in Damascus are still struggling to recover three weeks after it happened.
In a rare insight into life there ITV News has talked to some of those in Zamalka, a rebel-held suburb.
From Damascus ITV News International Editor Bill Neely reports:
Syria's rebels and Assad's soldiers agree on one thing. The military strike America is now preparing will change nothing and do no good.
As the threat of US strikes looms, people of Damascus wonder what missiles will achieve, and for whom.