The US is edging closer to a military strike in Syria in response to last week's deadly chemical strike. President Barack Obama and Secretary of State John Kerry have both spent the past few hours presenting the case for action. Obama described the use of chemical weapons as a challenge to the world, and a threat to allies in the region. John Kerry said the US is in no doubt that the Syrian government was behind the attack. And based on evidence collected by US intelligence services, Kerry said far more people had died than previously thought - more than 1,400 including more than 400 children. Al Jazeera's Patty Culhane reports from Washington. For the full story, click here: http://aje.me/1foY49h