Syrian opposition groups have reported as many as 1300 people died in a
chemical weapons attack carried out by the government in Ghouta, eastern Damascus. The French will act with force if proved true. The US are moving troops into position for a potential strike.
Area where the alleged attack occurred: Wikipedia
UPDATE FROM BBC:
“David Cameron and Barack Obama have threatened a “serious response” if it emerges Syria used chemical weapons last week, Downing Street has said….”